I feed Manna Pro Pro Rabbit Feed.
However, the bag says that there is NO CORN in the feed. This has been proven to be a lie. You have to watch, because several times I have found pellets with pieces of corn in them, and have found pieces of corn in the bag itself.
The only reason I haven't switched is because the breeder I got my chinnies from, Angela (Vyxxin), has been feeding this, and the chins are doing amazing on it.
I just make sure that I monitor their food/water intake and poop output. They have no problems (knock on wood!). If I see a piece of corn in a pellet (no matter how tiny) I throw the bowl away, whether it's full or not, and get a fresh scoop.