None are 100IV so they all suck, don't power up any of them.
lolno, if I were you I'd start w/ the highest IV Kyogre (14-13-15) and eventually power them all up. Groudon is trickier b/c you've got the weather-boosted version; I'd probably start with him (and save, what, 28 Groudon/rare candy) and eventually power them all up.