Rabbit Hole is my favorite. I’ve used Small Pet Select, mainly because they offer a rewards program and have discounts every so often that Rabbit Hole doesn’t have, but have never been THAT impressed. I just purchased some Timothy that my buns are meh about but the Orchard Grass they’re munching on a ton.
Oxbow, in the large boxes, I’m not too fond of but is the cheapest larger box option I’ve found on Chewy. It’s hit or miss honestly. The Orchard Grass I get is always good from them, but the Timothy is back and forth.
If you’re having trouble getting bunny to eat hay though, maybe switching from Timothy to Orchard Grass or Oat for a bit or using as a mix-in could be helpful. I buy all 3 since my chinchillas need the variety but I think the rabbits get a lot of benefit from having a choice as well. Orchard Grass is softer, but when I offer with Timothy and/or Oat Hay, I think they still get the necessary stalkiness for dental health.