I'm a three ish year vet of the cod series so I consider myself a pretty decent player. When it comes to kill streaks it really doesn't matter what you do or how anyone feels about em. Pick what you think works best for you. Though I'm a pretty cautious player (typically die under 8 times a game- not via hiding), I'm quite agressive. Assault could work, but I don't have the patience for it. I typically run heavy support. Uav > vests > nothing, recon drone or escort airdrop.
Uav> cuav. Or uav > vests is pretty mean. You are giving up a third ks, but if you can get 10 pr more kills a game you're really helping your team out. I like recon drone because in a game riddled with campers, it's a great way to mark them quickly (just remember to pull the trigger to actually target the guys). If you're team is good, a good recon drone round will utterly destroy the team. I had 18 asists once, that game ended completely one sided. The biggest thing for that ks, save it till you need it. I usually get it and hold it. Sometimes I don't use it, but for the most part around 15-19 kills I'll turn it on. I have no problem sharing kills with my tmates.
Many folks will say something along the lines that support is for noobs and that is an abusive streak set. F'em. that same thinking could be said about many things in the game, from shotties and akimbo machine pistols to semi auto weapons in the hands of a quick fingered player. Really, there's no wrong choice.
My only assault class is my sniper setup. 5+ kill streaks aren't hard at all for a good mobile sniper, that is when you get the hang of that style of play.
And then there's specialist. Very very fun. For poops and grins I use this one one at random times. When you get really high ks's on this one you start racking up mega xp and I love the sound effect each time you unlock a perk.