I started with a G22 Gen2 then two years ago added a G23 Gen4. Then I stumbled across a great deal on a used G27 Gen3. I prefer Gen4 and the smaller grip but not quite enough to replace the the older Glocks that I trust as I have lots of rounds through them. I'm glad the G23 is a Gen4 though as that size is just right for me.
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