Eh, all classes have pretty comparable weapons. The real difference is in the grenades and their effects when coupled with certain aspects of your progression tree (which is different for each class). I think each class has a weapon type they're more predisposed to getting in drops, though. Not entirely sure. The big difference is just in how you want to play and what Supercharge ability tickles your fancy most. I like having a huge AoE attack that I can launch in loops ever few minutes that guarantees a massive hit if I am smart with my timing. Hunters have their three-shot Golden Gun, which is good for PvP, but not as effective (IMO) for PvE. And Titan, as I said, is just badass to look at and deals a good bit of damage (also great for taking care of the trash that comes with boss fights).
Right now, my Warlock is level 18. I have pretty much kept with an auto-rifle as my primary the entire game (mine right now does something like 180 damage). That's pretty much what you get from all classes, though. My buddy is a Titan, and I swear he has been rolling nothing but fusion rifles and pulse rifles as his primary the entire game.
Also, weapon use is different depending on what you're doing. In PvP (unless I'm just doing it wrong), you need to have a good auto-rifle to compete. The charge time for fusion rifles just never works out in my favor, and pulse rifles don't do enough quick damage with the pacing that the Crucible forces you into.
I think Warlocks DEFINITELY have the best grenades, though. You can literally block off an entire doorway or side of a room if you're smart with them (and in later missions, they're great for throwing into the ridiculous swarms of trash you get thrown at you).
I disagree on the auto rifle for PvP. I got tore up by shotguns the first few matches I played,so I switched and now that's all I use. I'm a titan though so I can soak some damage up as I close the range gap.