Apologies if this has already been stated...
I would not recommend the Ultra Compact .45acp whether Springfield, Colt, Kimber, etc. However, I DO recommend a 1911 in .45acp caliber. If it's concealment you're worried about, be assured that a full size 5" barreled 1911 Government model EASILY is concealed on the strong side. in fact, I had an Ultra Compact Springfield for CCW and it was actually LESS COMFORTABLE than a full size 1911. I sold it ASAP.
The key is a quality holster, not the gun shop crap for $20. I would suggest an Inside The Waistband (IWB) holster. Check out Mitch Rosen and Milt Sparks holsters. Order now, because it will take 3 months to be made.
Back to the original question...a short barrel like the compacts are not conducive to such a heavy bullet such as the .45. The Commander/Officer's size barrel is as short as you would want to go...but I still recommend a full size. Read David Lauck's book "The Tactical 1911" and you will learn a lot.
As for Glock, they're reliable pistols. I would get a .45acp, 10mm, or .40 S&W (in that order) in that caliber.