Agree with all the above - Mine is a Colt SAA in 45LC. I sent it back to the Colt Custom Shop several years back and had a 45 ACP cylinder fitted to the gun so I could have both options. There are a lot of great guns out there depending on what you want and what your budget is.
Ruger has just come out with a John Wayne commemorative - limited edition engraved. Destined to be a true classic
The LC is a great all around cartridge. I shoot it in black powder from time to time - talk about a hoot; its better than New Years and the 4th of July all rolled into one.
I personally think that the Rugers are the best for the money guns on the market, and would go with the Black Hawk. My Black Hawks are all old 3 screw models but have shot and worked on some of the New Models and other than the triggers are good to go, I`m very picky about my triggers and you`ll probibly not know how hard they pull if your just getting started in handgun. If you do`nt like the trigger pull it is very easy to lighten them.
My preference for a single action would be the BlackHawk Convertible simply to have the .45 ACP cylinder as an option. As far as double actions go, I'd take the time to hunt down a good condition Dan Wesson while they are still out there. Being able to swap barrel lengths and use heavier loads than the S&W makes the difference.