The April 2nd game in Oakland, no doubt about it. Bradley's defense on Curry.
Speaking more generally, I really enjoyed all of the ways Isaiah Thomas manages to use positioning and footwork to get into the paint and score at the rim. Never gets old.
Also, seeing Jae Crowder turn into a running back the instant he catches the ball on the perimeter with a few steps of space in front of him. Just "pounds the hole" right to the basket. I looked at Crowder as an ideal backup SF and at best a decent starter. This season he shattered that expectation.
Every time Smart just gobbled up an entry pass with arms that seemed about 50% longer than they ought to be was a lot of fun too.
Finally, I know intellectually that the way Turner plays is not conducive to running a quality NBA offense in the big picture, but on the nights he has it going, his baseline fades and pull-ups just outside the paint are fun. He does things nobody else in the league does.