EPA has the ganja drug, which temporarily increases LU. That technically broadens possible character builds, you can now get Better Criticals/Bonus Ranged Damage even with starting LU1. Other than that, EPA is horrendously overengineered. The new map in RPU28 is nice, but it's only the ground level I think? And it doesn't solve the overcomplicated adventurish quests. Even worse, EPA is integrated with the other game locations - Abbey has a quest with it, and the mad Shi scientist too.
The Sulik's tribe camp while banal happens early enough in the game that I still have energy to go trough with it. Also it's one of the few game locations with coastal maps. And I always liked the small slaver map with Sulik's sister - just a small contained single map level with just enough opposition.
Abbey's redeeming quality to me is that it has a Stealth Boy, the only in the game.
The locations that I liked the least (apart from EPA) are around San Fran - the mad Shi scientist, the Hubologist hideout, the submarine. At that point I'm too burned out on the game to deal with all of the crap - can you just allow me to see the "Welcome to Enclave" animation and see the ending slides?...
That said, I'm too used to playing the game with RP so I still usually play with it.