Fire Blast
Flarephoenix's idea isn't attractive because hail doesn't have an existing base of good abusers. The stallers either suffer from 4MSS, bad stats, or reliance on Snow Cloak hax to succeed, and the attackers get smoked by Scizor. One new awesome thing probably won't make enough of a difference to make hail viable. Besides, everyone's probably sick of weather already.
There's no way Korski's idea will be usable in OU. It'll come out either too weak to do anything or too broken to keep the banhammer off of itself. It's a fun idea, though.
BMB and FB's ideas have similar goals; while I think that BMB's is cooler, I'm going Fire Blast because he seems to have more support, and I don't want to sway the election towards Korski.