Its hard to pick one really, but my least favorites are Sankeys and Eden, mainly because they feel like they could be anywhere, just big dark rooms, same also goes for the old Space discoteca to a certain extent.
Space is my all time favorite for the afternoon terrace sessions, Amnesia and Privilege a close second, love the garden and other rooms at Privilege!
Es Paradis is worth a mention too, just a lovely club, could really do with a good quality house night or 2 to bring it back on the map, then I might go again, I haven't stepped in there for 15 years or so!
Pacha is a weird one for me, its one that I always think yeah its alright, it never wows me