In Korea it's wonyoung and it ain't even close.
Outside of Korea especially both in Japan and China sakura got a bigger fandom. Obviously sakura is way bigger in japan.
I do feel sakura even outside of China and japan kinda beats out wonyoung in fandom power. But wonyoung has been attracting many international fans throughout ive and her status in Korea and visuals. I guess it'll be clear once the le sserafim debut happens.