Why don't you like the M4, if you don't mind me asking? I have extremely limited experience with the M4A1 (a grand total of 4 days using one

), but I really liked it, the only drawbacks are the weight of the stock (which makes the weapon pretty akward and unbalanced when you slap a 203 and one or two other goo-gahs on it) and perhaps the length of the barrel, which at 14.5 inches is somewhat on the short side for my tastes. But I would say it is far from being a bad weapon, it seemed to be very reliable (although I was constantly cleaning it in the field just to be safe) and highly accurate, and the collapsing stock made it much more manageable in certain situations (didn't do any urban, but I was climbing through some pretty friendly brush

).