I went for a free trial at Fitness Studio, Gurney Tower.
I did hear some bad remarks about instructors not being fit (or having bad stamina), but the class I went for last Sunday was great.
Those are local instructors (Sadly, it'd be more cool if they are foreign instructors like Celebrity Fitness).
Fitness Studio has a wide variety of classes and mostly of Lesmills.com.
I would consider the weekend package, which is only RM50/month.
(Same pricing as Priority fitness at Ivory Plaza).
With that, by comparing the 2 clubs, I would rather go for Fitness studio, as it provides better facilities (shower room, free flow of drinks, car park only Rm10/month, wide variety of classes).
Mostly importantly, i felt the pain in my butt.
It must be the ABT class that I attended.