I have many of the popular scopes in this price range and the only ones I've had any problems out of have been the Leupold VX-I. I've had a couple and everyone I've used has had to go back to Leopold for repair. They have great customer service, but that's about it imo. This all said I don't think the current model VX-1 (previous gen VX-II) is a horrible scope for the price. They have good glass, but I just don't think they are the quality of some of the competitors offerings.
That said, I've had pretty good luck with most others in this price range, but think some are better than others. I've also had a Bushnell Banner and a Trophy and neither are anywhere near the quality of a Nikon, Burris, etc. Everyone I've had has had sub par glass, horrible adjustments, etc. Once you step up to the Elite series they have good glass, but other than a tactical fixed power I've never had one that tracked accurately, which is a big let down for the price. In addition to this you get poor costumer service and other than the Elites you not only have to pay shipping to them if you have a problem, but you also have to send them a check for return shipping. This is unheard of with the other more reputable companies. I just see no reason to buy a Bushnell when there are soo many better options out there.
Now onto the Nikon Prostaff. I've had a couple of Prostaff scopes as well as several Monarchs. I'll focus on the Prostaff here though since it's in your price range. The ones I've had have taken some serious abuse and never lost zero. I've dropped them, banged them around, etc and they always keep on trucking. I also like the magnification ring because as mentioned it's way to turn with gloves on. The adjustments on mine haven't been repeatable, but on a muzzle loader most people zero them and don't touch them again. If that's what you plan on doing it's a good scope for that. If you are planning to dial in for longer ranges and need to be able to return to zero, this scope isn't for you. To me this isn't all that relevant on a muzzle loader though.
Next is the glass. This is really the only place I think the Prostaff falls short. The glass is decent, certainly better than a Bushnell Banner or similar but it's not great. They pick up a lot of glare if you're shooting in the direction of the sun and for my eyes, chromatic aberration is pretty bad if it's sunny out. This doesn't make them unusable by any means, it's just there. As far as other lighting conditions, they seem to do well. In low light they do decent. I've never had a situation during legal hunting hours where I was thinking I couldn't make a shot with a Prostaff.
Overall, I feel like the Prostaff isn't really great at anything, but is good at everything with good durability, decent glass, finger adjustments, etc.
Now, all of that said the Burris Fullfield II is also in that same price range and blows everything out of the water including the Prostaff. The glass on them is excellent. They handle glare much better, while the Nikon is just fine in low light, the Burris is much brighter. Glass wise I don't think you can get anything better until you step up to the Zeiss Terra. At least I haven't seen it if you can.
The Burris is also very durable and I've also been very rough on them and the hold zero very well. They have steel on steel adjustments that provide a good feel. They are just all around great in this area too. As for the reticle imo their ballistic plex is much less intrusive than the huge circles on Nikons BDC reticle, but this is more of a personal preference.
The only downside I see with these scopes is the magnification adjustment. On the original, when you assist the magnification the whole eye piece turns. This nakes it hard to run flip up scope caps as they'd constantly be turning when you changed the magnification. Imo this isn't a huge downside, but just something to consider if you want to run flip up covers. The newer E1 and C4s fix this though.
So all of that said, imo the Burris is by far the best choice in this price range and it doesn't really have a competitor rat even comes close. The Prostaff would probably be my second choice, and it's not a bad scope at all, but it falls pretty far behind the Burris imo. I've also had a couple of Redfield Revenges and Revolutions and while they aren't bad choices, I think they fall short in comparison to the Burris and even the Nikon. If you have any specific questions just let me know and I'll be glad to to answer them.