I love James Brown, he was hip, he was cool, he was innovative, so don't get wrong, but I'd be surprised if he would get more than about 20% of the vote if this same poll was run over at the Steve Hoffman forums. I could be wrong, but here's my thinking: We have a much younger crowd here at Head-Fi, and I think as the years pass, the appreciation for what Elvis managed to do in his career (and The Beatles as well) has diminished terribly, just in terms of the historical context of his/their contributions, whether you "liked" his/their music or not.
Anyway, that's my 2 cents. Again, taking nothing away from James Brown. I still listen to his stuff a lot, and he always gets the groove on, but he was no Elvis, IMO. To me, it would be like comparing The Beatles to The Rolling Stones. Again, taking nothing away from the Stones (and I truly do love their music, and listen to it even to this day, just like James Brown), but they weren't in the same league as The Beatles in terms of their cultural impact and the like.