Which food is best for Flowerhorn fish??? XO HUMPY HEAD or GRAND SUMO?

Either is fine. The thing with specialty flowerhorn food is you are getting charged more for it. It is the same thing as any other cichlid pellet. I feed my flowerhorns Hikari cichlid gold, Kens cichlid pellets, Kens soft and moist with krill, and freeze dried krill. They are all big and colorful with big humps. The genes in a flowerhorn have more to do with hump size than any food.