Or haven't even shot the Colt...
I've shot the M&P15-22 and love it but I wanted the M4 heft and look of the Colt. Good arguments for both but now that the price is about the same I'd recommend anyone in the market for a dedicated .22lr AR to look at both the S&W and Colt. The 180 degree selector swith is my biggest complaint, it was dumb of Walther to do that.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together. You'll remember the quality of a gun long after you forget how much you paid for it.
US Army 1966-69, VFW Life Member, Retired Geek