For ease of loading I would go with conicals. Patches are just one more thing to think about. I know you can get packages of correctly sized patches for certain diameter roundballs from T/C, so you should be able to get the right combo easily enough. BUT, conicals are just easier to deal with IMO. I have owned several T/C hammer guns and they all shot maxiballs real well. Other conicals have been hit or miss. Never tried Powerbelts.

I do make my own bullets. It is far cheaper, but you do need reasonably pure lead. Wheelweights will not work. If you go the roundball route, you may be able to change patch thickness with different batches of bullets, if your lead source/purity changes. The more alloy you have, the larger the bullets tend to be. Pure lead shrinks the most as it hardens, and the molds are made for the shrinkage rate of pure lead.

Many years ago I made a batch of maxiballs from wheelweights, and the bullets were so oversized that it was nearly impossible to load one. Those got converted into fishing weights.