A 'best' in anything signifies the most successful in the position. A captain with calm/precise/tactical attitude with the success rate of 2/10.. against someone very bold/impatient/implicit in strategy but the success rate of 5/10...clearly distinguishes who the most successful is. And the most successful is always the best(in the job, may Not be in personal qualities). regardless of the methods of approach.
Hence, whoever won us the most matches after a reasonable amount(maybe 10+ matches) of captaincy, is the best.