Pietersen and Malik have barely captained yet so I can't really make my mind up on them; Gayle still baffles me; Smith, Vettori and Jayawardene are all pretty good IMO; and Ponting as I say is middle-of-the-road. Kumble always used to strike me as pretty good but has apparently been poor of late.
Gayle is incredibly inspirational, the difference between the team when he's captain and when Sarwan is captain is crazy. Nevertheless, Ponting's experience has to count for something, though, maybe if Gayle goes on a while longer one can look back on his career and rank him above Ponting but at this moment in time i'll still have Ponting ahead.
Kumble's captaincy has been horrific since the Australia series (wasn't too bad in England- nothing special though). In that series, he chased the field, obvious missed opportunities (no leg-slip to Clarke when he was walking across his stumps to the spinners and getting edges- mistimed two shots in the air there before Kumble shut the stable door). Poor bowling choices, and his own bowling and batting suffered as a result. And when Dhoni captains the team, in ODIs, against SA and now against Australia, the improvement is unbelievable.
Vettori does a very difficult job at an awkward time for NZ, particularly since he's followed the greatest captain of the modern era IMO. His methods aren't unique and ground-breaking, but he very rarely makes mistakes or loses his cool. His batting and bowling haven't suffered in the slightest either, despite the fact that on recent evidence he is literally the entire NZ team combined into one man. As with his bowling, though, his captaincy is world-class in ODIs.
Jayawardene is a good example of how a fairly negative captain can still be a very good one IMO. He knows the pitches in Sri Lanka like the back of his hand, and his management of Kevin Pietersen this time last year was ingenious. He also has a knack of timing a declaration perfectly, is very calm under pressure, and utilises his unusual array of bowlers very well. Outside Sri Lanka, though, he's not nearly as effective, and his job is made a lot easier by having the dream bowler to turn to on any surface.
Smith is another whose captaincy has improved a lot over time- and is one of the best men to have under pressure in the game. His man-management is much improved, and he rarely makes big mistakes. Nothing inspired- with the loss of Vaughan, there are no particularly eccentric captains in international cricket- but he sets good fields and lets his bowlers do the work, which is as much as he can realistically do.
None of them, however, are exceptional captains in the way that Fleming is. I would say, as a Hampshire fan, that not one of them would have been in the same league as Warne had he been given the opportunity to captain at test level.