Our OTTB goes nuts for peppermints and watermelon rinds but they are a very occasional treat.
Our mare likes the rinds but thinks peppermints stink!
Most of the time our treat of choice is crumbled alfalfa cubes. They love them and they're healthy and cheap. The only time my horses would get alfalfa hay would be if I could find a diet variety! LOL
They do get completely spoiled on Christmas Eve. I mix up chopped apples, carrots, oats and molasses with some beet pulp soaked in hot water. By the time it gets to them it's a warm mash.....