Hi Dleung,
I have just dive at Mataking at the end of June this year. I wasnnot see the big fish in there but there are many kinds of different nudibranch I saw. And also I was saw the turtles, pipefish ,manadarin fish, frogfish and etc many time. Sorry that I was not go to Sipidan before, thus cannot compare.
From Mataking Island to Sipidan is around 1-2 hours depend on the sea weather. If you can afford the pay much money, the dive shop can arrange day trip for you to go to Sipadan.
But the resort in Mataking is good and the food is best.
Hope these information can help you!