Timothy or grass hay should be their main diet, with about a 1/4 cup of pellet food per 5lbs of bunny, and veggies as well.
Smudge has molar problems, so he only gets 1/8 cup of pellets. I admit there is a little alfalfa mixed in his hay since I buy it by the bale, but since he is older he has never had an issue with it, and it does help with his teeth. He usually gets romaine lettuce, parsley, and a little piece of carrot for veggies. I give him little pieces of dried fruit for treats.