I suggest you shoot both and see how you like them. You can discuss the features of both all day, however its redundant both can be modded for shooter preference. Which the bottom line is shooter preference, see which you prefer to shoot and pick the one you feel more comfortable shooting. Both are very capable weapons and can get the job done. I personally own both generations Gen 3 G23 and a Gen 4 G19 I love both of them. Both are very controllable to me. However the new double spring system in the Gen 4 makes the 9mm feel like a .38 or weaker. it feels great to shoot very low recoil. My G23 is very controllable as well the .40 feels great shooting any generation or model of Glock. Remember shooter preference is what counts.