I must say it's gotta be hands down silenced snipers. And then the fact that I will finally be able to have a secondary weapon such as a fully auto pistol or a shotgun. Will be much better when I am sniping.
Actually, for a Barretta .50 Cal in real life it can only have a flash hider and I heard in MW2 when you shoot a .50 cal gun it will have a flash. That would be cool to have machine pistols, but the problem is without dual magazines it will have short ammo capacity and machine pistols will have short range. The silenced snipers would still be awesome.