Powering up... general IV or ATK ?

In this particular instance since the DEF rating is the same I'd be more than happy to trade 3 HP for 2 ATK.

HP isn't as important for me usually.

2 extra IVs doesn't make any real difference is the base stat value is high.

Check for any relevant upcoming break points you might be interested in. If there is no break point difference the 13-14-13 (88) is better since Groudon base stamina stat is a lower stat than its base attack stat.