A top 100 artists list is inherently implied to be this, and it would be vastly preferable to some dumb calculations.
A favourites list should be the things you like most, not some things you like mixed with stuff you don't really like but included anyway cus they score high in your system.
For instance I like The Beatles a lot and consider them to be among the greatest bands of all time, but I don't listen to them very often and I don't have a significant personal attachment to their music. So if I were to rank them with a calculated system they'd probably rank near the top if not at the top (since they would have the highest number of highly scored albums). But in reality The Beatles probably wouldn't crack my top 50 personal favourite artists.