F2k has some nice stats but I don't think I'll ever be able to get over how ugly it is.
PDW seems like the best way to go, but if you save a bit longer the Shipka is highly suggested. It's good at everything, besides the fact that it has small freeze. In spar it's excellent at trapping people because it shoots 2 bullets both packing spread. Also it fires very fast a unique gun that has the shots of a shotgun.