the question, on a deeper level, is actually meaningless. the best style for winning is the style you can actually play. no one plays their style in order to lose.
that said, there is a hierarchy of playing styles. ranging from pushing to all-court. if you are, say, an all-courter you will win most easily playing this style, regardless of your opponent; provided that mentally and physically you are at a high enough performance level with respect to your capacity.
if you can only pull off counter-punching, then this will be the most effective style for winning, simply because you can't play a style that is above this in the hierarchy; similarly, why play the pusher game in this example? you will not win more easily or at all.
taking offensive initiative is great. it's what works best in tennis and many other sports. but if you are not good at it then it will be detrimental due to the risks, percentages, inconsistencies, etc.
what is more interesting and profound is the issue of how to play when confronted with adverse circumstances: poor form, lack of practice, match practice, particular shots that seem to have abandoned you, etc. coupled with the attributes of the opponent you are facing. then an all-courter may achieve bigger gains by reverting to, say, counter-punching. but this shift can only work in one direction - downwards; ie, it is highly unrealistic for a pusher to attempt serve and volley : ) , the poor fellow is hopeless, there is no lower style he can fall back on.
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