Yoda, Count Dooku

really the question is where do those toons need help in your opinion? That's what you should mod. Or you could take their strengths and bump them up to extreme levels, like add speed mods to Yoda to take his already crazy fast speed up a notch. Or adding defense/health to dooku to make him able to survive even more attacks, which would give him more counter areacks.
In my opinion, Dooku could use some potency. And unless Yoda is in the leader position, he needs some tenacity. In fact, both of those toons need tenacity, because when I encounter them the first thing I do is stun them, and although Yoda is fast I generally have a stunner or an ally assist available for attack before he gets his first turn.

Ok thanks

Ok thanks

Don't mod either, both are irrelevant in the current meta.