That's interesting... we have loads of ex-Accenture & ex-IBM folks at Deloitte too ;) Personally I'd recommend applying to a few companies, and go to as many presentations/drinks/informal evenings as you can. The people you meet at these events and interviews will give you a pretty good idea what the culture is like, as getting someone to describe something that subjective is practically impossible. Just talk to whoever you meet, ask them what keeps them in their jobs and with the company after 1,2,5,10,n years. Needless to say, I believe Deloitte have the best culture!