It'd be easy to say that the majority of players with pick the Assault package when choosing how to play Modern Warfare 3 in a few weeks time. Part of the new Strike package system, Assault is most similar to the traditional killstreaks.
But I don't think that will be the case. I think the Specialist package will get the most talented players attached to it. Sure, you won't get to fly a helecoptor or control a missile, but you get to become an overpowered super soldier and, in the right hands, that'll be lethal.
I'd also argue that the support package is going to be much more popular than most people think it will be.
The video above provides a little more in-depth information on the thinking behind the strike packages and the sorts of players that they've been designed for.
I know for a fact that, come November 8th, I'll be testing out each of these individually though. And sucking at each of them.