In world cricket today i would say Sangakara is the best wicketkeeper batsman closely followed by Dhoni. Sangakara has proved his mettle in all forms of cricket & specially test cricket where dhoni is yet to perform as a batsman!!
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At present level I think Mark Boucher of South Africa is the best wicket keeper cum batsman at present era who is still playing and also our own Mahendra Singh Dhoni both of them are good. but my vote will go to Adam Gilchrist of Australia. He is all time great. His records speaks his volume.