Mace Windu. If it wasn't for a blindside by Anakin he would have killed Sidious.
Mace Windu was being played and was going out that window regardless. You notice that Yoda was conveniently off-planet when Palpatine's true identity was revealed.
Honestly, if you know any amount of lore at all; Luke is far and away the strongest force user the galaxy has ever seen. You can hate it or love it, but Luke is a force demi-god. Abeloth had to be created to introduce real competition for him.