I don't think Colt ever did a .45 Super. That one should have been on the "other" list.
As far as favorites go, it would be my Delta Elite that Heirloom Precision did for me. It's hard to go wrong with .45ACP, though. I do really enjoy shooting the .38 Super. Feels just about perfect in a steel-framed Commander.
Shooting 9mm in a Government length gun will spoil you very quickly. Almost no recoil.
The only reliability problem I have in any of my Colts (1911 or otherwise) is in my Service Model Ace. It's really picky about which magazines I use. If I use the original magazine it feeds flawlessly. If I use aftermarket magazines, the pistol gets really picky about ammo. Some feed fairly well, and others basically won't feed at all. I basically gave up on the non-original magazines, so I can't even tell you which ammo the aftermarket ones seemed to like better.
As for a museum, well, I simply don't have that kind of scratch. If the OCD ever really takes over, I suppose I'd need one of each caliber in each frame size offered. Problem is, some of the models (like the Defenders and any of the "Enhanced" models) just don't appeal to me at all.
-Matt