Its mostly what your used to. I have used M4 since 2010 (Dug That Baby Up!) and since then have never thought of using a different gun.

Moral: Its all about how well you handle the gun, not as much how much money you spend on the gun.
Moral 2:I am really good.
Moral 3:Haha I said oral!... ._.
Im sitting On The Fence On This Because I had bought the Steam Punk Pistol one time because it was Over Powered, but it was very obvious it was overpowered (no freeze and 8 dmg. with fast firing rate...)

I am not sure If I am any help, but good luck with your circumcision!