Most accurate, Worst, favorite Muzzleloader you have owned out of the box.

[Buckskins & Black Powder]

Most accurate: T/C Black Diamond XR, but a PITA to clean, load, and keep breech dry in rain.

Favorite: CVA Wolf, good shooter with all loads I've tried, easy to carry and clean. Will flash rust if shown a picture of rain though.

Flitz Polishing compound

[pacecars]

The most accurate and my favorite would be my White Rifles Super 91 .504 stainless barrel and action with synthetic stock. the worst I had was a CVA Staghorn. It wouldn't shoot worth a darn.

[mcwoodduck]

Since I only own 4 front loaders it will be pretty easy.
Most accurate is the T/C Greyhawk in .50  the book said to start with an 80 grain charge, since I was using Pyrodex I measured out 64 grains and loaded a round ball.  I stuck a 1/2 dollar sized orange sticker my old company used for clearance items to a split log and walked back 75 yards.  Capped the rifle and took aim for my first ever black powder shot.  I hit the orange sticker at the 2:00 position.  knocked the log off the stump.  we walked up to check it and saw the hit.  Called it a fluke beginners luck what have you.  Reloaded the rifle with the same mix and proceeded to hit the orange sticker at the 3:00 mark and about 1/3 of the strike was over lapping the first hit.
At that point we called it deer ready and waited a few days for the season the open.
Favorite would be the Rem 1858 pistol as it is fun to shoot.
worst is my copy of a Zuave rifle.  Only because I cna not find enough of the Minie balls that the sights were regulated to hit.
All the .58 stuff I can get is hunting and they somehow hit either Hi or low with the weight and charge.  Also with the barrel fixed in the stock it is a pain to clean.

[Lawful Larry]

Best out of the Box:     NEF, Sidekick .50 cal.  Also the most reasonable priced:  $159.00 on sale

Worst:     T/C Encore, my biggest nightmare with any gun!!!

Latest purchased:     Knight Vision.  Very promising ML.  Will take into the woods this season.