I voted 32 man flights because the way the prereleases I attend are set up that way and it allows you to enter more than one time with decreasing entrance fees each time, plus I've never really participated in booster drafts or 8 man constructed at one.
The place I've gone to only runs a main event and a booster draft that doesn't start until after the main event is done. I've never been able to stick around that long, so the main event is my only choice.
I added a choice to the poll since I've only been to one and did the 32 Man event, yet still couldn't finish because of previous commitments (though it was pretty fun).