Here is my suggestion... Kalm UltraŽ Horse Feed | Tribute Equine Nutrition
This is what I feed my gelding. He isn't a HARD keeper, but it's tricky to keep weight on him. Plus, he has always been a little hot (anxious and distracted), but ever since I switched him to Kalm Ultra, he has really come around. It has a bunch of beneficial ingredients that help with his digestion and overall health, it's low sugar, low starch, and it has a higher fat content. It's pretty much exactly what he needs. He looks good, his hooves and coat are in fantastic shape, and he is always pretty mellow and level headed. He loves the flavor, too. He eats every bite.
I know everyone has their own opinions on all the different types of feed out there, and that is totally fine! Not all horses are alike and they can't all eat the same thing. I have done a ton of research on the ingredients in his feed and I feel totally confident in it. Just thought I'd toss it out there as an option to consider!