I have both - a G21SF and an XD Tactical. Little to choose between them as to reliability, durability, ease of maintenance, etc. There are two things that fall in the XD's favor in my opinion. First, I have smallish hands. I can make the Glock work OK, but the Springfield is a better fit. Second, I find it just a bit easier to hide the Springfield. Even with the long slide, I carry it in a CompTac IWB holster and the thing just disappears. The Glock seems to be just enough wider that it isn't as easy for me to conceal. The one thing I especially like about the Glock, though, is the fact that it works really well with a 10mm conversion barrel. So if I want real power, that's the one I pick up. Just a few thoughts.