Let f(player) = minimum(BW success, SC2 success)
Then f(Rain) > f(Flash)
Let f(player) = (BW gold medals) x (SC2 gold medals)
Then f(Rain) > f(Flash) (I think? I don't really know SC2. If Flash won anything of importance in SC2, this isn't true.)
On the other hand,
Let f(player) = maximum(BW success, SC2 success)
Then f(Flash) > f(Rain)
Let f(player) = (BW gold medals) + (SC2 gold medals)
Then f(Flash) > f(Rain)
So it's really just a matter of what semantics you'd like to use to argue for your favorite guy. Personally I never cared about SC2 at all, so although I admire Rain's BW play a lot (and would like to see more), I consider Flash to be in a league entirely of his own.