His Ballads album is probably one of the best albums ever made by anybody. It got dunked on by critics originally because they thought he was ditching his sheets of sound stuff from Giant Steps for more commercial appeal.

If you don't own it you should. Preferably the deluxe edition with his Greensleeves takes.

As far as his sheets of sound stuff, I think Sun Ship is ridiculously underrated and is a bridge between his classic quartet and Pharoah Sanders/free jazz era stuff. Really really good if you've never listened to it.