I have been diving around Asia before but Sipadan in Malaysian Borneo was definitely the best place I have ever been in. It was also favorite dive site of legendary Jacques Cousteau. I met people who had been there 20 years ago and even though it’s still amazing place for diving “it used to be even better with more diversity”. So if you are into diving you should get there before it’s too late.
Tip: Divers allowed to enter Sipadan per day is limited and usually diving packages should be booked in advance. Almost everyone dives with Scuba Junkie which is a great company but you will get the permit much easier with other companies. You might be even able to dive Sipadan everyday. I just had three dives there but they definitely were the best I’ve ever experienced.