Brilliance (also Amiga) was even better than DPaint. I haven't found anything to compare for just the plain fun of noodling about, since moving to PC.

The best follow ups by far were Avid Matador and Discreet Combustion.

Avid bundled Matador (and FXTree) into Softimage, which Autodesk later absorbed and killed off.

Discreet were also assimilated by Autodesk, and Combustion was later killed.

That's the second time I've heard Autodesk accused of the "Embrace, Extend, Extinguish" tactic in a week (albeit implicitly in this case). Is it something they are know to do?