Quality, reliability, and features.
The 1911 is a platform, like the AR-15 or the 4-door sedan. Compare, for example, a BMW 5-series, an Audi A6, and a Cadillac CTS.
Now, strictly based on MY experiences (and no one else's):
I have found Remington 1911s to be very nice. Same with the S&Ws. The S&W is different in that it uses a different (not better or worse, just different) extraction method.
I have found Colts to be absolutely reliable but somewhat of a mixed bag when it comes to fit and finish.
I have found Springfield Armory to be decent with occasional hiccups in fit and finish.
I have found Dan Wesson to be outstanding in build quality, reliability, and customer service.
I have found Rock Island Armory (Armscor) to be cheap, mostly reliable, and ugly as sin.
I have found Kimbers to be junk if they were made in Yonkers, NY--and their customer service to be wildly sub-par. Kimber tried the same method of extraction as what S&W uses and bollixed it up so badly they have recalled every pistol that uses it.
I have found Para Ordnance to be slightly above Kimber. Only slightly.
The unfortunate part is that Kimber seems to have the biggest marketing department!
