The brilliant Hartz Fur Fetcher is the absolute best brush for normal short to medium length bunny fur. It takes out the deep sublayer of fur that, if left, can become itchy for your bunny (or cat) and make the house look like it is covered in snow.
The photo above is from one run through of the brush on one of the bunnies here at the refuge.
The teeth are not deep so they won't cut your bunnies delicate skin. It really is the best thing for your bunnies.