Anything you want to feed them. They don't do too much difference between them. If you got the cash, go with the more expensive brands or better yet, feed natural instead.
I used to use Mana pro, but now use the cheapest stuff, no difference in the rabbits. They are pastured though, so don't need the pricey foods.
I have Netherland Dwarfs and feed them around 1.5 ounces of food daily, along with unlimited hay supply. Juniors, still too young to breed, but not weanlings, also get a measure amount. Around 2 ounces, depending on how much weight they are putting on, sometimes 1.5 ounces. Before I feed the rabbit, I run my hand down the back of the rabbit. If the rabbit is a bit bony, more feed; rabbit is more filled in, less feed.
I use PenPals 16% feed. Usually rabbits need no more than 16%. Once again, it all depends on your breed of rabbit.