I’m not going to be able to write a heartwarming, beautiful post about why I love Seohyun. But I can try my best to explain why she is my ultimate female bias:)
I despised SNSD earlier this year. Ever since day one. I refused to give them a chance. Why? Because they’re so beautiful and I saw them as flawless. I was jealous and felt inferior. And when I was watching We Got Married, the site I use mixed up Yongseo and Khuntoria for an episode. Right when I saw Seohyun was from SNSD, I literally said “HELL NO!” and refused to watch them. But since I was nearing the end of the Adams couple, I pushed myself to watch Yongseo. I didn’t know what to expect. I was going in with a strong dislike towards SNSD. But Seohyun changed my heart. She’s very different from most girls. I hate the admit this, but I thought the SNSD girls were going to be somewhat ditsy. Seohyun is way more intellectual then any person I’ve met. I didn’t expect her to be a bookworm. I thought she’d be all about guys but she’s the opposite. She is so innocent. She never really liked a guy before. She basically turned my whole view on SNSD upside-down! She’s unusual. She’s not abnormally outgoing and hyper like the other Soshi girls. She seems to kind of stay in the back and keep to herself… Yet she is still active and able to show she can have fun. She’s also very humble and well mannered; hence the meaning of the Banmal Song. She did things that most girls wouldn’t do on dates. One of Yongseo’s first dates was in a bookstore. And she bought Yonghwa books and requested him write book reports. Then for another date, they donated blood together. She also takes wonderful care of herself. She eats healthy; Goguma obsessed LOL. And makes sure she gets to sleep at certain hours so her skin cells grow.
I really don’t know how to word and explain my admiration for her. But I tried. Basically, how she proved me to be 100% wrong about my close-mindedness towards SNSD started this love. I don’t know all the Soshi girls well. But Seohyun is the one who shines the brightest in my eyes. How she’s so different from the typical girls I know just puts a smile on my face.
[most of this is based off what I’ve seen in Yongseo.]

I hope this answers your question well.^^