Either will work. The G22 is going to be cheaper ammo. A 9mm's ammo is cheap enough that you essentially make up the different in savings from 40 to 9 and get a G34 or G17. That's why the 9mm is so much more popular.

The $ difference between reloading 9mm and 40 is comparitively miniscule. If you were reloading 40 already, I would just say go with the G22. Factory ammo is different. No reason to not start out with the G22. The holster and pouches are the same and you can always switch to a G17 or 34 later or reload.

If you can pick up a used G17 on the cheap that's in good condition, I can point you in the right direction on basic parts and do the work on it for you. An LE trade-in is your best bet. Make sure the slide to frame fit is tight. You can see this by watching the back of the slide as you pull the trigger on an empty chamber. The more the slide moves up from the frame during trigger pull, the looser the fit. A little movement is always going to be there. A lot of movement is bad. Tighter is better. Don't care if it's got holster ugly all over it. You are just going to draw and shoot and reload the piss out of it anyway.

New sights ($70-$100 if needed, the factory plastic ones MUST go into the garbage), some basic trigger mojo ($0-120 depending on just how light you want it) and a lighter recoil spring (less than $10 if you want it)... done.