Sorry...Lang Lang (or is it Bang Bang by the way he plays) is on my "most over-rated" list. And yes I have heard him in person on more than one occassion, not just on CD.
I've heard Kissin twice, once a recital, and once playing a Brahms concerto. Excellent.
Another one I also like (in person again) is Arcadi Volodos.
I've heard Menahem Pressler many many times both solo and with his trio (Beaux Arts Trio). The only person I will go out of my way to hear.
Another favorite live who is probably unknown to you guys is John Lill from the UK. He is a Tchaikovsky winner (1970).
http://classicalplus.gmn.com/artists/artist.asp?id=1010&bio=true
I might be coming at this differently because hearing them live is different than Memorex. They can't monkey with the sound or edit things in or out. I like hearing them raw.