I bought a G-20.4 and use the smallest backstrap and Talon rubberized grip tape, My wife likes it and so do I but I have the Springfield XDM's that I like a smidge more. I did not put a lot of thought behind Gen 3 or 4, all my other Glocks were Gen 4, including a G-29-4. I have five 10MM's so while they are all good I did a 'Shoot Off' with my XDM's 4.5 and 5.25 and the G-20, the G-20 shoots a little softer than XDM 4.5, but I like the grip better on the XDM. I think the G-20 is a great choice anyway. Gen 4 works for me.