I have been following this thread with interest. It is indeed a difficult question, given the limited facts that we have, so I have not voted yet. A few theories that I have to give some thought to:
1. Casey killed Caylee in her bedroom, which is why she slept in Cindy's room for 10 days straight......
Well, the reasoning that KC had to sleep in Cindy's room came from Cindy. I think it had little to do with KC's sorrow, and a lot to do with Cindy doing everything she could to keep KC isolated from Female Body Guard. She would be especially on guard at night, when KC might talk in her sleep or otherwise ramble on in FBG's presence. I don't consider KC sleeping in Cindy's room as any sign of guilt on KC's behalf.
2. Caylee accidently drowned, as alluded to by the ladder not being stored properly.......Again I have to consider the source of that story. I think it was George that confided to LE that Cindy called him and dressed him down about the ladder and the gate. Why was George volunteering this interview and the limited info he gave? After studying the interview, it was my feeling that he was testing LE to learn what LE knew, so that he could learn how to respond accordingly. Also I think he wanted to nudge LE thinking a bit.
Cindy and George, by most everyones way of thinking, knew Caylee was gone. They couldn't bring themselves to accept that Casey was purposely responsible. The most innocent scenario that they could possibly hope for was accidental drowning. They surely wanted to convince themselves of that, along with LE and Casey. I felt as I watched the interviews, that they were leading Casey to go with the accidental drowning scenario. I think they made a show of moving plants and boxes to re-enforce their theory.
Was it true? I dunno, but the source of the possibility was George and Cindy, so I have to take that into account. If the duct tape around the head rumor is true, I'd discount accidental drowning.
3. Casey killed Caylee in the car in a fit of rage after a huge fight late on the 15th......Was there a huge fight? Including choking? What are the sources? Mark F reported that neighbors of the A's told him of a loud verbal exchange in the A's front yard, but they were uncertain of the date. Casey told Lee who told JG about a fight on the 15th, which involved choking. Can we believe KC's version?
There wasn't a choice to vote for "Caylee fell off of the balcony at Tony's apartment". Good, 'cause even though LP pushed that theory for a while, I don't think so.
H Poirot said we could change our mind later, so I now vote for the car, and more specifically the cabin, not the trunk. I'm not very certain of my vote though. I wouldn't bet a cup of coffee on it.