If you're not after a Colt 1893 clone, then I'd say the Ruger Blackhawk like everyone else as it's built like a tank and can take pretty stout 357Mag loads to mild 38sp ones.
If you're after an 1873 clone, I'd say the Ruger New Vaquero although it isn't functionally 100% identical since it uses a transfer safety bar and one way indexing cylinder.
Closer to the 1873 clone, Pietta is on the economical end. They're pretty solid performers and good value for the $$. Next up would be the Beretta Stampede (though similar to the Vaquero ie uses transfer bar), Uberti makes some awesome ones and the El Patron model is factory tuned. If you want smooth, tough to pass up a Taylor & Co SAA.