Ordinarily I'd suggest EVO out of those, but the company was just sold to Proctor & Gamble so the formula will probably change relatively soon. Even if the quality doesn't drop, I'm sure you don't need to mess with a formula change.
I would probably go with one of the Nature's Variety formulas.
I know there are some foods that are "oatmeal based" but all the ones I've seen have other grains in them as well.
I definitely know what it's like trying to find a food that works. Logan did GREAT on one food for 2 weeks, then had diarrhea yet again ever since