Personally, I think Keenan's food is better than Roy's, but I'm also not a huge fan of Roy's. I think of Roy's as the Ruth Chris or Morton's of Pacific Rim cuisine - all decent chains, they serve good food, are far from being the best restaurant in town, but they get a lot of business because people are familiar with the name. The exception would be the original Roy's in Hawaii Kai which is significantly better. I used to live near Aulani, but we'd drive across the island to Hawaii Kai Roy's even though Ko Olina was less than 10 minutes away.
If you're looking for a restaurant with a menu/experience similar to Roy's, try MW Restaurant - that's where the locals go. Coincidentally, Keenan and the owner of MW went to school together. Another classmate of theirs runs a plate lunch spot called Hamada General Store. Those two restaurants represent some of the best, modern takes on authentic local (not Hawaiian) food.
https://mwrestaurant.com/https://hamadageneralstore.com/