I think Chidori is pretty damned draining, but ... sasuke is nowhere near being able to summon something big (like gamabunta for example), and he can still do two shots of Chidori without exploding his heart or fizzling the attacks out. Remember that Kakashi's four-shot limit is coming from the same guy who readily admits to being unable to use sharingan for a very long time because he tires so easily using it.

I'd say ... as far as "genin with the second most chakra capacity" ... well, neji does have that whole whirly thing going on, which is neat and all. I don't think Lee uses a whole lot of justu-style chakra, he's pure taijutsu. While the whole "opening the gates" thing is unleashing chakra, I don't think that he really knows how to control the chakra and move it around as much as he knows how to flood his body with it and speed himself up as a whole, so I don't think he's a candidate. Sasuke.

If you want to say "character (non-monster) with the most chakra" I'd say right now Naruto's still behind Jiraiya and probably Orochimaru as well. I think of course he'll surpass them all in raw capacity soon, but I don't think he's there now. We've seen orochimaru do some freaky-ass things, and ... well ... Naruto's base capacity wasn't enough (without calling on Kyubi-chakra) to summon Gamabunta (though this is up in the air, we don't know which chakra he used to summon Gama in the Gaara fight but I think it's a safe bet that it was Kyuubi-chakra that went to work without Naruto really asking for it - he still has that whole "I'm about to die" reflex that kicks in, whether he can access it consciously or not).

Since we know that Jiraiya can and has in the past summoned Gamabunta (and found him to be quite a handful), I think it's safe to say he's at least at the top tier.