Dhoni may be a better captain when compared to Kohli, but I don't think that he is among the best.
Anyone who understands and watches cricket for multiple decades will tell you that MS Dhoni is one of the best captains in the history of cricket. I would rank Clive Lloyd and Steve Waugh above anyone else because the way in which they dominated world cricket under their captaincy and under them they refuse to loose and that was their dominance. Under MS Dhoni India learned to win series abroad and dominate oppositions with tactical moves which even surprises the opposition and i would rank him along with Ricky Ponting and Hansie Cronje.
If you think that he is not the best in the history of world cricket, i would like to hear about your list whom you think are better than him.