AK74 w/ grip & rapid fire is good (I have it on one of my load outs), but in general it's hard to take anyone's recommendation on what's "beastly" when the games are so laggy. I can be beastly with the stock MP5K over any other class given the right connection advantage.
On a side note, I could be wrong, but I think that if a teammate is in the process of capturing one of your care packages, double tapping x to re-roll with Hardline Pro will not work. I dropped one, got killed, then rushed back after respawn, teammate got there a couple seconds sooner. I suppose I could have just grabbed it's contents overtaking his capture, but instead I was mashing x to get something better than a counter spy plane.