glock 22 gen 4

Look to purchase my first gun. I have my choice narrowed down to three guns: 1. Glock 22 Gen 4 2. Glock 22 Gen 3 3. Springfield XDm 40 I know the legacy of Glocks, but have heard mixed reviews about the Gen 4's. I heard the XDm are very reliable modern handguns. Any suggestions, pro/cons...