my first (and current due to newbitis) is a SRC M4A1. i get a lot of compliments on the gun, from the sturdy construction, so the darkness of the tinted lower.
shoots great, but could use a bit faster of response time.
i prefer the M4, due to the shorter barrel, i'm more of an attacker so i like my barrel close to me, but not to the point of have a CQB.
i'd say try an M16 out, if you find it too long, go for an M4, its basically the same gun