go to Kensfish.com
He has some really impressive foods and a lot cheaper than you can get at your LFS. He has tons to choose from but just look through the ingredients of the foods that interest you and pick out the ones with the best ingredients.
Don't feed very large foods, especially pellets. Geos tend to do better with smaller pellets and don't make as much of a mess when chewing them. Nothing bigger than 2mm pellets at their current size.
I'm feeding my baby Winemilleri the "slow sinking growth pellets"(1.5mm size) and they love it. Plus I feed them various other store bought foods just because I'm trying to use it all up. They also like Tetra crisps, all my other fish do to.