I think Jack Nicklaus was the best pressure putter of all time. I think they may split in match play- but in my opinion, Nicklaus would win out on the greens.
Found this too:
From Golf Digest-
Nicklaus won 18 professional majors, including four U.S. Opens 1962, '67, '72, '80), five PGA Championships (1963, '71, '73, '75, '80) six Masters (1963, '65, '66, '72, '75, '86) and three British Opens (1966, '70, '78). Won the U.S. Amateurs twice (1959, '61). Won 70 tournaments on the PGA Tour and was leading money winner eight times. Played on six U.S. Ryder Cup teams.