Re: What is the best gun?

It really does depend on the map / game mode / the composition of your squad / etc.

I think some guns aren't as good as others, but in the right hands, any gun can be as effective as any other. 

You weren't asking for opinions, but I do think this is an opinion question as well, so I will cast my vote for the AEK-971. 900 rounds per minute, decent range (though not as good as other ARs) and lower stopping power but it makes up for these shortcomings w/ its ridiculous rate of fire. For CQB, it's the best assault rifle by far IMO.