I tend to prefer damage per shot over high firerate except for my handgun. There a high firerate is key because you generally only use it after emptying a magazine, not able to reload quickly, so you have to do little damage in little time. Above all I love sniping, I got the M200-SV, the most powerful bolt-action gun, since it's more stable and powerful than auto-snipers. As for assault-rifles I also go for damage over speed, using sv versions mostly, once again more based on control.