Never regreted any attraction at WDW - ride or otherwise. They may not be my most favorite thing to do, but regret - no, not regret.
They only ride I have ever regreted going on was at Six Flags Great Adventure a long time ago (1980's) It was one of those centerfuge things where after you get stuck to the walls, the bottom drops out (do they even make them anymore?) Not for the spinning of it, but because my friends and I were trying to turn upside down and onto our stomachs so we could do upside down push-ups on the wall (as encouraged by the ride operator) I moved wrong and my head snapped around and the side of my face got planted into the wall of the ride. I had a sore neck the rest of the day.
-dave