For the beginner, I'd suggest a Remington in .44 caliber, made by Uberti, and with a steel frame. Here's why:
1. The sights are better defined. More hits promote confidence. As much as I love my Colts too, beginners are often frustrated by the Colt's meager sights.
2. Lead balls are readily available in .454 and .457 inch. Though many sources suggest .451 inch balls, it's best to use .454 or .457. Similarly, though many sources suggest .375 inch balls, it's best to use .378 or .380 inch balls. Finding the larger .36-caliber balls on a local store shelf is nearly impossible, but the larger .44 balls from Hornady and Speer are common on shelves.
3. The Remington design has fewer parts for cleaning.
4. Arguments that the Remington, having a solid frame, is stronger than the Colt are moot. We're talking black powder pressures. Hodgdon 777 is probably the "strongest" black powder substitute you can buy commercially, but it is also useable in a Colt 1860, Dragoon or Walker, all of .44 caliber.
The Colt design is amply strong for sane black powder, Pyrodex or 777 charges.
5. The Remington is available in stainless steel. No one makes a Colt design in stainless steel, anymore. They were offered a short time by Colt in the early 1980s, but to my knowledge no stainless steel Colt designs have been offered since.
Newcomers are often lazy about cleaning their revolvers. It's why you see so many new-looking cap and ball revolvers with rusted bores and chambers, sitting in pawn shops.
Stainless steel will rust, make no mistake, but it takes much longer than carbon steel. Stainless steel is more forgiving about negligence.
6. The Remington design can be had with modern, adjustable target sights. The Colt cannot, Some folks may not care so much about authenticity, but prefer greater accuracy. For them, the Remington is the best choice.
The above said, I still love my Colt pattern revolvers. They point better, are not so bulky, lighter on the belt and are just as accurate as the Remington if fed a proper diet.
I shoot both designs, with equal enjoyment. But for the beginner, I'd suggest an Uberti 1858 Remington .44 in stainless steel, with perhaps modern adjustable sights. Or not, if the newbie wants authenticity.