ORIGINAL: wabi
Just curious, what is the best you've owned?
To be fair let's divide the group into 2 classifications - open sights & scopes.
I've been burning black powder since the 1970s, and probably the most accurate open sight gun was a T/C .36 Seneca. I know that goes against the "
bigger is better" theory for a round ball gun, but I could (and have) shot 3 shot scores of 30/3X with that rifle shooting offhand at 100 yards! Of course the sights were a lot clearer back then, seems like they all use those cheap sights that look fuzzy these days!

For scoped muzzleloaders I'd have to give #1 honors to a Remington 700 MLS (stainless). Consistant sub-MOA accuracy with a variety of bullets!
A close #2 would be a T/C Omega. One of the early ones, and it would keep them close to MOA or under with a few different loads. About 1.5 MOA with 150 gr charges!!!!!!!!!!
Think back and remember the "sweet" ones, then do like I do and beat yourself up mentally for letting go of them. [:@]
The Remington was a pain to disassemble to clean for me, and the Omega was lost to a weak moment when a newcomer in muzzleloadingasked me where he could geta good used rifle.

The Seneca went because the .45 barrel I bought for it made the balance terrible, and I couldn't use it for deer hunting. Accuracy with the .45 barrel was terrible - not the barrel quality, butthe balance was just too bad to be able to hit anything offhand. I wanted a deer rifle, so I traded the Seneca on a Hawken.
Best I have owned... I would have to say my Omega because it was 100% reliable and easy to clean and just a joy to carry and shoot, not too much technical info to find a good load and bullet, and I have shot a lot of deer with it. However it can't beat my current Savage 10 ML shooting smokeless for accuracy, but that rifle is a bear on "little things" that affect accuracy---seat the bullet firmly on the powder with all your weight on the ram rod, very tight sabots not loose, very strong primers not the 777 or Kleenbore, 300g flat based bullets not 290 boat tail tmz, clean your ventliner every 25 shots not 100 which is what some folks say---so you have to be "into Savages" to get them to shoot anything other than the book loads. Book loads of XTP 300g, 5744 power 44g, short black MMP sabot will shoot 1.5" out of the box, getting other bullets to shoot is a whole new ball game. I like it, it is fun, but I am very glad I bought my Savage last year for a Oct 2008 hunt in Colorado for elk, I would NOT have been ready buying it now.
In the Open sight category, I also like Flintlocks, with open sights, but I am not the most accurate with those, nor do I shoot them extremely well, I need more practice. I have a TC Hawken .50, and I just switched the barrel to the Green Mountain Carbine. I have not shot it yet, so I don't know if it is accurate or not. I know GM is top shelf, so I am sure it will be, oh it is 1:28 twist for sabots.
Chap