The ROA is the gold standard. You'll never lose money or enjoyment with one.
If you do not want one of those, the Remington New Army 1858 copies are the most forgiving replicas to shoot for a new shooter. It's the design that the Ruger Old Army was inspired by. Easier disassembly than any Colt clone, no opportunity for the manufacturer to give you one with a short arbor (don't worry about what that is right now, but trust me: If you buy a Colt copy you'll need to learn about it and how to fix it). They are easy to load, easy to clean, shoot well, and are a pleasure always.
Which 1858 copy? Well... you basically have Uberti or Pietta.
Traditions, a common discount store trade name, is a Pietta. Cabelas sells loads of Piettas too.
Uberti's are sold under the Cimmaron name, but also under their own name, as imported by Taylors and Stoeger. Quality is identical for Cimmaron or Taylors imports.
Advice:
I'm a Uberti guy: The Piettas are OK, and getting better, but the general concensus is that the Uberti's are a grade better in quality. For certain they don't suffer from the garish "shoot with black powder only, made in Italy" markings on the side of the barrel like a Pietta. And in a 1858 the Pietta grip is mishapen as compared to an original. The Ubertis are closer to being correct.
In addition you need caps, balls, powder (try to buy the real stuff please!), a powder measure/flask combo with a 30 grain spout, and maybe some bore butter. Then go shoot! You'll figure out anything else you need on your own.
A VERY pleasing finish for them is the "Original" finish, which replicates a well used revolver, and makes your normal handling marks just blend in. I always suggest it. You can do a good job of antiquing them yourself with a washrag and some vinegar, but the factory aged ones look grear right out of the box.
Willie
.