I met Deleuze briefly but had no conversation, and attended his classes for 6 years – this is one of the greatest experiences of my life. I had a couple of conversations with Lyotard. These two philosophers are the most impressive I have ever met, and their seminars were the most impressive that I have ever attended. The intellectual freedom and originality, extreme concision and conceptual resonance of language, the sense that a new philosophical world was being created before my eyes, an intensity of attention to what was being said as if it were all up for grabs and was continuously being rethought instead of just repeated. I would add Michel Serres to this short list, for the same reasons. I met all three in 1981, and have met noone comparable since.
This is my response to the question posed on the DAILY NOUS here.