The obvious choice is procreate! I was a studiopaint die hard, now I only draw in my freetime (which is much better), and settled on mypaint a few years ago.

I don't own a tablet yet. But procreate, Paper, and the various stylus available are now very tempting.

I am just as happy now to watch the ipad market undertake the design market, as OS9 and NT did against IRIX. Watch us do more with more accessible consumer tech.