I really like Elixr I prefer the smaller clubs and the more personal service you seem to get at Elixr. If you're after high-energy then Elixr might not be for you as the vibe is a little more relaxed - but that works well for me as I go for the pilates and the yoga - although they do offer kick-boxing and also spin etc at the Bondi Junction club.
The quality of the pilates instructors is generally really good - especially Rachel's classes - I'm usually stiff for a couple of days after one of her classes.