Depends on what you're hoping to see mate.
I study elasmobranchs so I'm always out looking for small sharks and rays because that floats my boat and there are plenty of both around Mettams. Have you tried mettams recently? Great vis and saw quite a few fish there this week.
If you're after normal fish then I don't really know dude. The reef at just south of the Cottesloe groyne is pretty decent, albeit not protected from the swell. Although we have none at the moment. Heaps of different fish in there, the endangered seadragon (been trying for 2 years to find them), the occasional small shark, rays, all sorts of cool anemones and other cold water corals and sponges. I've had a few dives there now where I've had two dolphins come and hang out with me for half an hour or so between bouts of smashing the local bream population

Depends on what you're after I suppose.