I've worked on Tioman. I was mainly in the Salang beach area, but I've stayed on Ayer Batang (ABC) beach as well.
Salang 4 dive centres. B&J (my old crew) Azmi's, Dive Asia and Fisherman's. B&J caters for a more european crowd, whereas the others seem to attract more Malay and Singaporean guests.
The accomodation on salang is reasonable. You can get a fancy air-con/ hot shower room if you wish. But With a tropical heat, a hot shower isn't all that inviting.
ABC has an B&J branch as well; the main one, where the boats moor for the night. Then there's Eco divers, a small dive shop where the staff never stay for long and they don't visit many different sites. This is not bad-mouthing, I know the staff of Eco quite well. A couple now work for B&J. There is also a Japanese dive centre on ABC, but they tend to dive off of the B&J boats.
Again you find what accomodation you prefer here. What's nice is the Sunset bar at then end of the beach; great pizzas and mojitos while the sun goes down and a great vibe. Other restaurants are ok.
Tekek; the main town has a few dive centres, but I couldn't tell you the names as I've never met them. Although Tekek is great for Duty free booze, that's about all that can be said. I wouldn't stay here.
However you can get off here if you're going to stay at the Berjaya Resort. It's the islands 5 star resort; although most people say it's only about 3 star. Accom is expensive and you a limited to what you can do off an evening due to it's distance from everywhere else. Also they resort dive centre is not that much cop, and other dive centres may charge for you to be picked up from there.
Paya, supposedly has some nice resorts, but I've never been so cannot comment.
The same goes for the other beaches on the lower west side of Tioman. These may have nicer accom but you are a looong way from the main dive sites.
There is one beach on the east side, but there is hardly any diving over that side so would so recommend. But it is a good chill-out spot.
Main dive sites to hit would be. Chebeh, Labas, Golden Reef.