Koh Tao--worth it?

Hi dive community! I'm going to be in SE Asia next summer and was looking for a land-based dive resort in Thailand to end the trip. I know a few people who got certified in Koh Tao and liked it, but after getting in contact with a couple of dive operators, I'm feeling really put off. It feels like their primary motivation is selling us the AOW course. One operator said we wouldn't be allowed on their "advanced" boat or to descend past 18m without it! I'm nearing 150 dives and my SO has over 350 and we've been all over the world and never heard this type of restriction, so this was a bit insulting and felt like an obvious money grab. I'm getting the sense that Koh Tao has its reputation mostly for being an easy, cheap place to learn. Has anyone been to Koh Tao who didn't get certified there? Was the diving anything special? Is it worth a side trip from the mainland? Do you have a company you recommend?