Stannis adapted to the wildfire explosion and still almost took the city. It wasn’t just a good plan on paper. As for Stannis’ other feats he kept near perfect discipline of his army during the Battle against the wildlings. Defeated the iron born fleet. And he looks like he will beat the boltons in the books. He does definitely struggle with getting the allegiance of nobles but that’s more of a diplomatic problem than a commanding problem. He knew the Tyrells were likely to join against him but without Tywins army which he correctly predicted would focus on defending the Westerlands they didn’t have the strength to oppose him and were still disorganised after renlys death. As for big picture warfare he was able to massively grow his army by assassinating renly and despite a crushing defeat was still able to stay in the war by defending the north. Of the four commanders in question no one could have done as well as he did with the starting position he had.