Don't get me wrong, Kukaku's cool as shit and for interaction stuff I'd readily take her over Komamura for both being more relevant to Ichigo as ghost-kin, and being an all around more amusing/less stiff character.
This said... I can't help but feel that Kukaku's a waste to go bother now, rather than later.
She gave us a pretty clear timeframe estimate on when the message sending'd be ready - a month - and it's not been close to that. I just don't see the point in going this early, to drop off a message that we may well want to change in the interim, as opposed to trying to give the message closer to the time of sending. Say we go a week later, rather than now - that's a week less early the messager needs to be for us to run into them, and a chance to cross off the Komamura visit before more shit comes up/we forget/etc., and we miss a chance to chat with a guy that seems to have some real interesting Bankai insights.
I still feel that Ichigo's family and return/contact thereof is the most core and important of goals for the PC - I don't think that means we must go prep our message for no particular reason. As I said, things could change (maybe Ichigo meets the Shinigami assigned to Karakura via a connection, and can tip his family off he'll be having them bring messages all official-like, or maybe he'll be going on a school mission that'd prevent him from sending/getting further messages for a while, or what have you) between now, and when that message actually goes. Out of date post suuuuucks, and I don't see a benefit for risking it, when there's an obvious benefit to avoiding it.
And hoping to run into Yoruichi for her secret Bankai stuff reeks of OOC knowledge as a motivation for the vote, as we (A) Don't know about her, (B) Don't know she's got skillz, and (C) Don't know about the Bankai training shortcut she has. Komamura on the other hand we (A) Know about, (B) Know is a captain, and (C) Know he invited us and from school have fair reason to think we could ask him about Bankai stuff given his position and what it says about his Zanpakuto skillz. This, against the only fair IC reason to think of the Kukaku vote for Bankai stuff being... the cousin who we don't have any reason to think has Bankai.
So yeah, meta and narrative, I think Komamura's a better pick right now than Kukaku.
EDIT: I also really, really hope the people voting for Shikai are not assuming we already have sizechange - that is what Zangetsu will give us on getting Bankai by the deadline, not what we currently have - we still bang things with our huge clumsy sword, like our friends, which is no bueno.