Here we have the raw data for all Test captains. Naturally the W/L ration is undefined for those with no losses:
Here we have everyone who captained in 2 or more Tests without a loss.
This list is headed by WW Armstrong of a century ago with 10 Tests including 8 wins and 2 draws, followed by DB Close (7 Tests, 6 wins and a draw).
Those with an all-win record are A Bacher, today’s Babar Azam and Lord Hawke who all captained in 4 Tests.
Also note AM Rahane with 5 Tests, 4 wins and a draw.
However, this list would be more meaningful if it was restricted to those who captained in 10 or more Tests.
Here we get:
As mentioned earlier, WW Armstrong is the only one here with no losses. Next come Jardine, Bradman and Steve Waugh. Waugh has the highest ration for those who captained in 25 or more Tests.
From India, V Kohli is the only one.