Getting back to the original question, the world champions Anand, Topalov, Kramnik, Khalifman, Kasparov, Fischer, Spassky, Petrosian and Tal have all played the Benoni at one point or another, but the Scandinavian is much more of a rare bird. Anand played it once against Kasparov, and Alekhine experimented with it, but other than that the world champions have tended to shy awy.
I dont think Khalifman deserves to be included in this list of "champions". He was more a chumpion imo. I feel the same towards a couple of others as well.....
Getting back to the original question, the world champions Anand, Topalov, Kramnik, Khalifman, Kasparov, Fischer, Spassky, Petrosian and Tal have all played the Benoni at one point or another, but the Scandinavian is much more of a rare bird. Anand played it once against Kasparov, and Alekhine experimented with it, but other than that the world champions have tended to shy away.