Summer Y!Tiki IV?

Depends what skills you're going to give her / have around the team (ex: flier buffs, chill spd). My style is to go +spd even with the atk bane because I'm probably using flier buffs and she usually targets an opponent's lower stat (most melee units have low res, and adaptive damage vs ranged). I'm the type that hates getting doubled because it means extra damage and I might get hit with a special (plus, this Tiki really can't take more than one hit to her res except maybe from some lower atk green mages).

+atk with flier buffs might net you some OHKOs, so it's to be considered (ex: two goad fliers puts her at 60 atk I believe? Most non-blue ranged units will fall in one hit).