Holosun is the ticket. They're a bit more cash than your usual replicas but well worth it. They're actual RS sights so they keep their zero and they're very durable from what I've seen. Do a bit more research on them but I believe these are the best optics for serious airsofters.
https://holosun.com/
OpticsPlanet usually has a descent discount code running if you decide to pull the trigger on one
https://holosun.com/
OpticsPlanet usually has a descent discount code running if you decide to pull the trigger on one