Help me i can't decide what to do.
You will still be able to use the other weapons on engi, yes I guess rifle is the more viable of the 3 (not counting hammer, don’t have an opinion on that yet) in pve.
As you’ve bought the game, you have more character slots so I suggest creating an engi, a mesmer and a necro, and try them out. Only you can decide what’s fun to play for yourself.
I won’t enter in the whole “meta classes” debate (e.g. necro is not wanted in dungeons etc…), because we’re just 2 days away from HoT and… yeah, just not going there :P
The elite specializations in HoT are completely optional. Given the extra effort we’ll need to unlock them and the complaints I’ve heard about some of the elite specs, I wouldn’t be surprised if a lot of people just stuck with their base class.
I’d also recommend making several characters so you can try different classes until you find something you like. I made several characters within the first few weeks of getting the game (mesmer, necromancer, warrior, guardian, maybe thief) and fooled around on them all for a while until my interest settled on the necro, and I’ve been maining him since.
I am incredibly biased with my engineer because I like explosions and playing the condition damage game. Engineer is viable for Power or Condition damage and brings a lot of utility to a party that will only be expanded come HoT. That being said, if you don’t like continually swapping in and out of Kits, then engineer is not for you.