Uberti was the brand to buy at one time. Pietta has upped its game. As a general statement, Uberti’s tend to look better, but Pietta’s seem to have fewer issues. While you are only asking about 1858s, Uberti has more platforms in their offerings. Look up posts by @45D for a perspective from someone who works on these replica handguns. Personally own a number of both Pietta and Uberti. Most any issue you encountered can be corrected. Comes down to your time or money, at least for me. Then there is what suits your fancy and fits your hand.
Pedersoli is the best one. If you only wanna shoot round ball then pietta will do. If you think you may want to try conicals then uberti is it. The piettas the rammer extends into the loading port and personally i cant stand that. It also has a slower twist rate.I have an uberti, one in 44 and one in 36. I haven't had any issues and they shoot great. That and pietta doesn't have the dovetail front sight, so if your gun doesn't hit POA your SOL. Pedersoli is the gun the others wish they were. It's what the competitors over seas use and almost always what the winners use. It's in a whole other league though. About a $1300 dollar league. I will get one sooner or later.
Maybe check out the link below. Just additional stuff you can’t access right now. Personal opinion, but if all you are interested in is traditional muzzleloading, you may be good with what you have access to. If peaking under the hood and engaging in other maybe not what one would always call traditional muzzleloading topics, consider signing up and paying a bit for that privilege . https://www.muzzleloadingforum.com/account/upgrades
That is the very reason why I won't "upgrade".
