M-16A2 5.56mm
M-4 5.56mm
SIG-552 5.56mm
G-3 7.62mm
G-36 5.56mm
AUG 5.56mm
FAMAS 5.56mm
FNC 5.56mm
L-85A2 5.56mm
IMI Galil 5.56mm
AK-47 7.62mm
AK-74 5.56mm
AK-101 5.56mm
AK-103 7.62mm
TKB-517 7.62mm
The best assault rifle will be of coures one that is most accurate, most reliable, cheapest etc. But that is pure fantasy. In the real world there has to be trade-offs. So when I compare m4 to ak-47. I would pick m4 anytime cause it has less recoil, more accurate, better range and one could fit in lots of goddies on it. Sure, m4's not as reliable as AK, though its not as crap as its made out to be by some folks.
I can take care of the reliability issue by proper maintenance, meaning, I'm in control. But no amount of training will make a rifle shoot straight if it has trade off accuracy for reliability.
The "Kel-Tec_RFB" seems interesting.