Yes, a question I've long found fascinating. These three formed, joint with the South African triplet of Schwarz, Vogler and Faulkner, the most potent spin attack in history during Indian cricket's most successful phase to date, the last 6-7 years notwithstanding.
So who was the best of the three? Am open to pretty much all myself, but I have read material suggesting Chandra was the most accomplished overseas performer, which to date has meant I've tended to consider him the best.
Venkat, the backup spinner, was always thought inferior by most despite the fact he was picked ahead of Prasanna on a number of occasions. So he's not included here.