Been thinking about scratching my inner Clint Eastwood and getting a single-action six shooter.  Any recommendations?  I'm most interested in reliability and durability.

Both. I own the Cattleman and have shot the Vaquero... Both excellent guns. Just a matter of taste. Uberti is more of a replica of the Colt where the Ruger is not quite but close...

What caliber are you thinking of?  I have a Ruger Blackhawk with both the 38/357mag cylinder and a 9mm cylinder for some cheap plinking.  There are several other dual caliber options as well. 

I have an Uberti that has held up well over 10 years or so and have had zero issues with it.   It is a more accurate copy of the SAA as @bhunted has said. The Ruger would probably prove to be more rugged over the long haul.

It depends on what you're looking for and of course price.

You are not going to find a winner in this thread.  Both guns are awesome, and beautiful.   I love Ruger and Italians make really good single actions.  

Both?