The G20 is a fine pistol for sure, but I'd go with the G21 instead...why you ask?
It can run 45 and 45 Super and 10mm with a barrel and magazine swap... its simply much more versatile overall.
You may even pass on 10mm altogether after reading up on the 45 Super.
The 21 is also likely to sell faster if you decide you want something else
This is true, but the Glock 20 10mm can run a .40S&W conversion barrell as well. Which is silly - I don't see why the Glock 21 can be converted to 10mm but not 40S&W... that's why I have BOTH.