The Hobbit rules include a few changes that make a Moria force more effective. First, Cave Trolls are not actually useful thanks to the additional Monster Attacks (and other Monsters on the list become even more effective). Second, the nerfing of bow fire means that Giant Spiders and Wargs (and Cave Trolls for that matter) have a better chance of closing the distance to melee where they are useful.
But a cheap Goblin swarm is one of the key aspects of most successful Moria lists. Lots of models helps absorb losses and overwhelm your opponent. Cave Trolls, Giant Spiders, Bat Swarms (as an opponent I find these are frustrating to deal with most of the time) and Wild Wargs are all relatively affordable options to boost the force. If you go with a Drake, Dragon or Balrog (all of which should be better now with the Monster rules) you will loose your number advantage so you really need to play a different game. Another advantage of these monsters though is you don't have to paint as many Goblins.