ddjj1991, nothing wrong with a Glock 21, but don't pay $700 for it. Even a new gen4 G21, which comes with 3 mags instead of 2, should only be $650, or less.
The 21 is definitely bulky, but the SF (gen3) version, or the gen4, are smaller in the grip, and fit most people's hands better. Or, look at the G30, for a more compact version.
Glock's 45's, for some reason, are a lot more accurate than their 9mm's and 40's; I think if you're wanting a high-cap .45, the Glocks are the way to go, either the 21 or 30.