Actually a good percussion cap sidelock is easy to load, shoot and clean. Take a quality sidelock like a Thompson Center Hawkins and shoot Triple Se7en, APP, or Pinnacle powder and patched roundball and they are easy to clean up afterward.

Any rifle you shoot has to be cleaned. You might as well get used to it. In the modern inline rifles I would think the drop blocks like the Omega, Revolution, Persuit, Kodiak, or Sidekick would be the easiest to load, shoot, and clean.

Actually I have a T/C Black Diamond XR and most people claim they are a bear to clean. My personal opinion on my Black Diamond, Wolverine II or Staghorn is, I do not feel they are all that bad to clean at all. Once you have cleaned them a few times you learn short cuts. Meaning, you learn what to clean first and how to clean it properly. I can clean any of the rifles in around 10 minutes, 20 minutes if I take my time and relax. Cleaning them is all part of the sport. If you want a muzzleloader that is most forgiving for cleaning then get a Savage and shoot smokeless powder.