Fabric has an AWESOME sound system and the best acts (DnB haven) but like most decent London Nightclubs is becoming quite touristy.
Herball, Egg (in Kings X) and OnAnon (awesome views over picadilly neon lights!) are all excellent.
A lot of people like Cafe de Paris which is £15ish to get in and very glitzy. Haunt of celebs and models. But I just dont like in. Too cheesy. And a bit...well, ****.
My favourite is AKA/The End. For big nights they join the two together and those nights are unmissable. Awesome club which is packed out full of very cool people and HOT women. And me. Which is all the hot man you'll need.
I like Wax Bar as well. Kinda clubby feel.