I would pick hidden power for coverage over bad iv reductions, but generally Ground is arguably just as good in this case anyway (HP fighting hits Aerodactyl, Munchlax, and Clefable harder, but they aren't all that hard to deal with at this point, and the final team probably won't have any problems with them) and HP ground is a little better to hit Qwilfish, Lanturn, Drapion, and Entei harder (as far as common threats go)
Personally, I think a case could be made for either at this point, but keeping the perfect speed ivs is always a plus with a hp