My daughter has a gluten-free brownie business -
www.sweetgirlbrowniecompany.com. She uses rice flour. They've been tested and are certified GF. Everyone who tries them says they're the best brownies they've ever had. It's fun to go to a tasting event and watch people try them. First, there's the "O" shaped mouth, followed by "That's the best brownie I've ever tasted!"
She used to make several varieties of brownies (non-gluten, spiced, orange), but the GF have been by far the most popular, and I like them best even though I don't have to eat GF. By the way, these are NOT a health food - LOL.