is it worth it?
 

1st is it worth it to buy a triggerfish and not have anything else?
2nd would a trigger kill a lionfish or vice versa?
3rd wat kind of trigger should i get?

1- its a personal preferance, I wouldnt
2- lions and triggers are usually a no no together
3- depends on tank size and what you like

I know Humus are nice as far as triggers go but I was able to keep a Volitan Lion and a Humu Trigger together with no problems.

johno4 is right, it really depends on the tank size. But i think just having a trigger is worth it. Them and puffers have very unique personalitys and really get to know who feeds them :) Probaly the clown, humu, and queen heart have the coolest personalitys as far as triggers go, but the clown can be a little mean, all depends on the specimen really, lol.

If you are going to get just one trigger, get a mean one, like an undulated! I've always wanted one, may setup a species tank just to get one. I'd also say it depends on the tank if it's worth it. If you have a nice huge tank, then one trigger isn't worth it. Just get multiple tanks, that way you can have the best of all the worlds, haha.