im torn between luke and yoda. i love yoda. hes plain awesome. he mastered every form of lightsaber combat there was at that time. mace windu was second to him in that respect. he stayed lightside for so long (he may have turned at some point, but that would still be insignificant to his time spent in the light.)
i heard yoda had a special talent for force push/telekinesis powers. that he could push through any jedi's defenses and give them a good shove. (can anyone confirm?)
im sure yoda came across a lot of obscure force techniques in 800 years
i always thought of luke as a pansy. because hes supposed to have the same MC count as anakin (80% sure about that), but unlike his father, he doesnt get 70% of his body mass chopped/burnt off and had access to far more force knowledge/powers. you'd think he'd be ultra powerful... but he was not portrayed as such in the books that i have read.
but that completely changed when i read LotF. they did him justice.
He smashed the living snot out of you-know-who, who was more powerful than vader at that point. and luke was like, 60.) LotF also shows that he has knowledge of quite a few obscure force techniques like jacen solo did. look how powerful jacen got with those.
its extremely tough. i wish i could vote for them both...
but my vote goes to... Jedi Grand Master Yoda!
i find it quite nice how the two most powerful jedi ever were master and apprentice.
(i always thought jedi lords would be almost superheroes... but farfella was pathetic! i cant remember about hoth. i personally believe yoda, mace and luke qualify for that title if it were still in use in their eras)