My View:
Dayang- Sea journey is longer. There's a possibility of securing a sleeping berth or space to lie down for some of the ferries depending on number of people. Accomadation is basic, I like Dayang Blues as it's quad share, has toilets behind and is generally cleaner as people usually bother to wash their sandy feet and keep the place dry. The dorm style accomadations is rowdier usually but very sandy. Most dive sites are nearby meaning you usually get to come back to the resort after every dive. Good variety of sites for beginners to the advanced divers. No hot water showers on the island. food is ok but not great. I usually bring some food of my own there. beach is a nice whitish sand for beach lovers. jetty is next to resort so no need to walk long distances.
Tioman- Sea journey is shorter, but the ferry timings are not accurate esp on sunday returning. As a result you might be waiting for a long time at the jetty. Very good dive sites off the coast like tiger reef, magician's rock, etc. resort and food in general is much better than dayang with hot water showers. There's also an option of eating at food stalls if the resort food doesn't interest you. That will depend on which village you stay at. Jetty might be a fair distance away from resort meaning a long walk. Distance between dive sites usually means you go out for 2 dives in the morning before coming back to the resort for lunch.
I wouldn't say one place is better than the other. Just what your individual preference is. I prefer dayang. If i wanted to dive tioman i rather do it by LOB.
