Everybody has their own gun preferences. I'm tempted to say buy what strikes your fancy. I did. But I shouldn't have. Since I'm new at this too, I'll just tell you what I did - and in hindsight, what I think I should have done instead.
I caught a couple of sales; for $160 I bought a brass-framed Pietta replica of a .36 cal. 1851 Colt Navy "Reb" revolver with a 7 1/2 inch barrel from Taylor & Co. of Winchester, Va. A spare cylinder came with the gun. Unbeatable deal if money is an overiding issue, -and they may still have a few of these guns. It'll get you into black powder shooting at a rock bottom price.
Then, for $199 from Cabela's, I bought a steel-framed Pietta replica of a .44 cal. 1858 Remington New Army Model revolver with an 8" barrel. I also sprang for an extra cylinder (for about $55 bucks more as I recall).
I'm actually happy with both guns, because my wife loves the smaller Colt Navy replica and is going to go shooting with me. I'll use the NMA replica.
However, I'd originally intended to buy just one gun and an extra cylinder. I let the low price for the "Reb" Navy Colt replica influence me too much when money wasn't really an issue with me, and in the end I needed another gun to go along with it. If the Colt replica had been steel-framed so that I could shoot 30 grain loads behind an 82 grain round ball, it would have been ok, or if I'd just been able to buy a steel frame to swap frames whenever I wanted to, that would have been ok too, and I wouldn't have bought the Remington. However, it turned out that a spare steel frame would have cost almost as much as I paid for the brass-framed gun. I didn't want to pay that much for just a frame, so , since I realized I was limited to about 15-18 grains of powder if I didn't want to damage the brass frame of the Colt replica, I bought the Remington NMA too .
From the get-go, I really wanted something a little more powerful than what I got with the 1851 Colt Navy replica. What I should have done instead is buy the $199 Pietta replica of the 44 cal. 1858 Remington New Model Army from Cabela's. If you'll look at a photo of one and compare it to a photo of a 36 cal. 1851 Colt Navy, or a .44 cal. 1860 Colt Army, you'll notice that the Remington has a steel top strap above the cylinder. The Colt's don't. That steel top strap makes the Remington a much stronger gun than any cap and ball Colt. Not only that, but changing cylinders in a Colt is a real prouction, but it's a snap in a Remington NMA. Cavalrymen with Remington NMA's used to just keep an extra cylinder or two loaded and on their person, and use them like we use speedloaders today. They could do that because the Remington gun broke down into just 2 pieces, 1. a cylinder and 2. everything else. It was much easier for a cavalryman (or anybody else) to change cylinders on a Remington than with a Colt, because a Colt broke down into four pieces 1. a cylinder ; 2. a barrel , 3. a tiny wedge, and 4., everything else (frame, handle, etc.). You needed a lot of hands.
Nevertheless there were more Colt Model 1860's used by the Union Army in the Civil War than Remington NMA's, but by wars end the Remington NMA was quickly catching up, and the Remington was definitely the gun of choice between the two, because of its strength, ruggedness, and ease of swapping cylinders in the gun. I love mine. It fits my hand and points perfectly. It's got an 8 " barrel, but it's so well balanced that it feels "handy". It's just not as pretty as the Colts, I admit that. (No prettier gun ever made than an 1851 Colt Navy model.)
NOTE: Never carry a spare loaded cylinder with caps on the nipples. one of them may accidentally discharge and hurt or kill you, or someone else. Soldiers in the Civil War just did it because the risk of an accidental discharge was less than the risk of being out of bullets.