I don't know a lot about feeds but, Tribute is a really great brand. They have a wide variety of feeds for different horses needs. They have ration balancers, low starch feeds and just about everything else. My horses are on their Kalm N EZ pelleted feed and grass hay. My 12 y/o gelding gets about a pound and a half and my 28 y/o mare gets about 2 pounds a day split into 2 feedings. Both horses are in excellent weight and condition.
Oh, and at my barn they use this same feed for the mules and donkeys, which are extremely picky eaters.