Oxbow is a very good brand, never heard anything bad about it! I use it for mine but it is expenisive so when I used to have more rabbits I would get large bags from the feed store of their brand of rabbit food which was always fresh.
If you just have one or 2 rabbits I would stick with Oxbow. Mazuri is good too, not a huge difference. Make sure to also have timothy hay available if it is an adult rabbit and alfalfa if it is a young rabbit!