I'm sure others will chime in with their feeding ideas. Also, you can check the archives, there have been many discussions on feeds and feeding (check out the search button at the top of the page).
I feed my minis grass hay. Up until a week ago, they were on Progressive Nutrition grass balancer pellets (which I really liked), my supplier decided not to carry the PN any more, so we are back to square one (I live in the middle of nowhere, so choices are slim). So, I have changed to a 12% complete pellet and some rolled oats; our grass hay is so-so this year, so added the complete pellet for better quality fiber plus the vitamins/minerals in it. They are also getting BOSS (black oil sunflower seeds) for their coats; one gets 1/2 cup per day, the other gets 1/4 cup per day.
In September, when Tana comes home (weanling filly), I'll be feeding her Nutrena Life Designs Youth with grass hay.