The greatest picks globally to counter 麦林炮手 include 百裂冥犬, 狂野女猎手, and 解脱者. These champions are all good at countering 麦林炮手 with high win rates over 56%. Even if these 麦林炮手 counter picks are not taken in the same position as you, it's not smart to play her into these matchups. They will most often win against 麦林炮手.
Yet, if the other team brings either 龙血武姬 or 扭曲树精, you should strongly consider selecting her, as she easily destroys these champions with win rates over 53% against both ofthem.