I quite agree BenChek's points. But SA80 isn't too bad. It is just bit shorter than the others. Once you get used to hold it in your arm, its firing power and accuracy are definitely ok.
I don't remember the range of M16A1, the experience of firing a M16A1 is one word "confidence". I tried AK47 as well, I felt it was too powerful for me and had less chance to hit the target once the barrel heated up.
People may argue that one hit one die with AK47. I can tell you that any wound caused by firearms could be deadly in the field. For close quarter combat, you don't have time to think of the mechanism of your firearm, just too quick.
Hollywood or John Woo style ain't working!