The 21 would be a good choice. I can't remember the number of the 10MM but it is the sames size and packs a good punch. It was the most accurate of all of my Glocks. Yea to say I was into handgunning big time is an understatement. I was selling guns at that time as well. I would give my left arm to have that first Auto Ord 1911 back. I loved that gun. It was getting a little loose but thats what made it so dependable. It was not super accurate but for what it was for it worked great. It would shoot 2 1/2 inch groups at 25 yards so it was not a Bullseye candidate.