Some of the comments seemed to respond regarding 44 magnums, or 44 Specials, when the question was about 45 Colts. Since you don't seem interested in the heavier loads, these are the models I'd consider.
The New Vaquero is a great gun and handles 45 Colts very well.
The Ruger Flat Top and it's available in 45 Colt and also in the convertible if you think you might like to shoot 45 ACP's.
Another gun that is very popular is the Flat Top in the Bisley version and it's also available both ways. I personally think the variety of 45 Colt ammo on the market is excellent.
I like the Original Vaquero in 45 Colt and have a few. I also like to add a SBH hammer to them. Makes it handy.
The standard Ruger Blackhawk, is a very nice gun as well and is also available as a convertible.
Sure there are other models like the Model 97 which to me has a small grip and it also has a short cylinder, if you want to shoot a heavier bullet. I've had a couple of those but was never happy with it for that reason.
Several companies make a SAA variance from Uberti to Beretta and more, but it's hard to find a stronger gun for the price that will last.
