So I own a fair few armies now, and have played many many games with them. So I'm going to start a tactical breakdown of the armies I have used regularly to use as a beginners guide for anyone looking for that sort of information. I know I would have loved that sort of resource when I was playing my first dozen or so games. Each unit that I have used will have a rating out of 5 and any that I haven't I will still rate the unit give a reason why I haven't branched into it yet. Also a small blurb on the overall strengths and weaknesses on the faction. So without further ado

Isengard breakdown!!!

So Isengard are the most forgiving army I've played with. The fact that all your units stats are between average (shoot value,movement and courage) and good (defence,fight value, strength) + the insane level army bonus means that you can mess things up and still grind your way out of trouble. Your fight wins often end in kills, your losses often end in your warrior surviving, and your army often only 'breaks' in the turn before it hits 25%
This army wants to be a phalanx army and does a good job of it. Your shooting is quite good and you have the point for point king of magic in the game at your disposal. The limitations on Isengard are no historical allies (and you don't want to lose your bonus) few cavalry characters, and none who have the isengard bonus which means your heroes often get picked on and beat up by enemy cav heroes. Your heroes are incredible at messing up waves of warriors, elite units and other cheap heroes of fortitude. Your army is generally pretty slow also. You want to use your high strength shooting to deal with cavalry and try to dictate the terms of the game. Then grind the enemy into dust with your high fight and strength warriors.

Take if you like a grindy phalanx army that's solid and easy to play
Do not take if you're looking for a fast army, or a 'top tier' army

Ratings key
1= trash. Compares unfavourably to any units available in game. no reason bar fluff to use
2= poor. There are better available units in the army that fill the same roll. may still be okay/average compared to similar units in other armies. A poor choice, but might have applications.
3= Solid comparatively to similar units from other armies, or the only unit that fills this necessary role in the army. A good solid choice.
4. Awesome. Your bread and butter. This unit stacks up favourable point for point with most similar units in the game.
5. Must have/broken/ the enemy cries when they see it.

A (*) means I personally haven't fielded this particular unit

Heroes of legend

Saruman the white
I highly recommend white boi Saruman in any game of 650+ points. He is the 1 and only weapon you have to shut down rampaging enemy heroes who outclass your own. (think Aragon, Dain, Thranduil heck even Gothmog on warg ) He can threaten cavalry with his socerous blast, shut down monsters for the game and protects himself well. Huge utility and well worth the points. 4.5/5

Grima Wormtounge
Basically an upgrade to saruman. Fantastic little disruptive unit who will often be well worth the points. There are ways to shut him down, but he can be very frustrating for the opponent. Getting him near your phalanx is key because that's where the action will be happening. 3/5

Heroes of Valour

Lurtz.
He's a tricky boy to asses. I have used him many times, and I still am undecided if he's trash or treasure. He has a strong range of heroic actions, 3 might and a very solid special rule in find the halflings. He also dies to a papercut and is outclassed in combat by every combat hero of valour who can ride a horse, and even many mounted heroes of fortitude. He murders troops and even monsters but he's very pricey to be killing GI joes

We'll call him a 3/5. Happy to discuss this one.

Heroes of Fortitude.

Ugluk.
Sadly trash. He just isn't as good as the other scout captains, his special rule is generally surplus to requirements in an Isengard force. I'd take him over a vanilla scout captain, but I'd never take a vanilla scout captain. 2/5

Vrasku
Here is the gold standard in scout captains. shoot 3+, expert shot with a crossbow, an extra point of might, heroic accuracy. This bad larry is the best baby sitter for uruk crossbowmen/ scout bowmen bar none. He's also still an uruk captain in combat, and points efficient enough that bashing enemy troops is just fine for him once the battlelines meet. Almost an auto include. 4/5

Mauhur
Cheap and cheerful. The best captain at bashing enemy troops up, and can give you access to speedy uruk scouts. Solid in smaller games but probably surplus to requirements in larger games. He also looks like a scout corp dude from attack on titan. 3/5

Sharku
Our first cav character. But the song remains the same. Good at bashing troops and junk heroes, bad at fighting anyone who can actually fight. He costs 2 goblins more than a warg riding captain with shield. So the question is... Is 1 might and a situational special rule worth 10 pts? Hard to say. 3/5

Thryden Wolfsbane
AKA Wolfsbae. All the stats of an Isengard captain, but with multiple weapon options and a horse!!! Hallelujah!!! He also has mighty blow and a 12 inch stand fast! He's a bit pricey and loses the Isengard keyword but honestly he's at the head of the pack. A touch soft to shooting. 4/5

Uruk Hai captain.
Due to the fact that with a shield they are D7 and the high fight and strength value, these guys aren't too bad an option imo. They can give you a bit of speed, and can comfortably grind away safely against large numbers of enemy warriors. 3/5

Scout captain.(*)
Trash. All the named scout captains are better options. 1.5/5

Dundeling chieftain(*)
Seems medium. I'd sooner have a captain for the points. 2/5

Orc captain(*)
No reason to take them on foot. I think on warg they're a good option to lead warg riders. 3/5

Minor heroes

Shaman (*)
Isengard isn't an army that can maximise the value of fury, and 5+ to transfix with 3W 1M is a bad beat. I don't see him as a strong option. 2/5

Independent heroes

Uruk hai drummer. (disclaimer, never used one)
Basically a scout with a drum and a point of fate. Considering drums cost 15-25 pts he seems reasonably costed. But I'd sooner take the troll drummer. 2.5/5

Warriors

Uruk hai scouts.
With shields this is a unit that can sneaky fast get across the board thanks to woodland creature and is just as survivable against S4 as your regular warriors w shields. S3 bows are also nothing to turn your nose up at. Wouldn't give one a banner though. 3/5

Uruk hai warriors with shields or pikes
Your bread and butter. Great against s3 units. Medium but solid against S4 This unit can grind with the best of them, and pikes are a useful tool, especially when you outnumber your enemy. Best option for a banner as well. 3/5

Uruk hai warriors with crossbows.
A fantastic shooting unit, an excellent strategic tool to dictate the terms of the game. This is almost a must take unit and one of the strengths of the army. 4/5

Orc warriors. (*)
Mordor is a better choice for these boys, and even they don't generally take them! 2/5

Warg riders.
Your only fast unit. Solid, S4 is nice and wargs hanging around occasionally is nice too. 3/5

Isengard troll.
F7 D8 gives heroes nightmares and can even take a drum. This is also the only combat unit capable of getting heroes of valour off the table regularly barring Thryden. 3.5/5

Berserker.
2 attacks. The versatility of a hand and a half weapon. C7. A free fury save. D6 against shooting. These boys are excellent and versatile. 3.5/5

Feral uruk hai. (*)
Slightly cheaper than the berserk boys, but you lose the hand and a half sword, a point of D, 2C and the D6 against shooting. This unit is very unfavourable when compared to the berserker. 2/5

Dundeling warriors. (*)
Not that cheap and not that good. I'd sooner take scouts. If you desperately want 2 handed weapons in your army, take Berserkers. 2/5

Wild man of dunland (*)
Worse than an orc against all but rohan. 1.5/5

Demolition team (*)
A unique unit that I've never used makes this too hard to rate. High risk high reward stuff.

Assault balista. Lets end on a high. A very powerful siege unit that stacks up favourably against many others. 4/5

Only two points to add/discuss from your analysis... because I agree with most of it.

1. Generally I agree with you on the drummer on his own. But brought as part of Mauhur's marauder upgraded warband with a Drummer allows them to March up 14 inches turn 1. And then if you choose to use his second might - another 14 Inches. That many f4/s4 troops flashing up a flank to either stall an enemy or even take them unawares and pounce on positioning can be huge. Even more so if you've got your normal phalanx getting itself set up on the spots you need it to hold! Don't underestimate that one!

2. Troll loses shield for the drum. I realize it helps all of Isengard but dropping to d7 is a major turn off IMO. Do you agree with that or would you generally not drop the defense for the minor speed buff?

I'd rate the uruk-hai drum a 3, maybe 3.5. Extra movement is valuable. Your only option for cav is wargs, and Wargs test for being broken at 50%, before your heroes or other troops, and are only C2, so are likely to run before the end of the game; the drummer makes your army more mobile without spending might or taking a risk on models that are fairly likely to run away. A troll drummer costs 100 points more than the uruk-hai drummer as well; that's 7-11 more Uruks/berserkers on the table, and maybe a banner.

Of course, that does depend some on how many points you're playing, but I'd rather bring a troll with a shield for D8 and an uruk drum than a troll drummer even in higher point games. I've often found myself wishing I'd had a drum in games at ~600+, because the infantry were a bit too slow to reach objectives.

Just a heads up your score changes from 5 to 10 in places

Shaman are still pretty competitive simply due to all of the terror causing models out there.

Ugluk is low defence but his extra might balances this. His special rule is less useful due to the army bonus but it’s also a feature that can help you remove your own minis which is occasionally useful for ending a scenario while you’re still winning.

Sharku is great, never had a game in which he’s performed badly. High might orc captain, great for leading any cavalry element.

I fixed the /10 thing.

I hadn't considered the implications of fury vs a terror causing army.
Cheers for your input on Sharku!! I'm still convinced a troll drummer boi is the way to go. You want a troll anyway to pressure enemy heros and control the battlefield. Might as well slap a drum on him if you want a drum in the army.

Isengard is a very strong army.