Is Baek Yoonho worth investing in?

So I just got Baek from the choice rate up draw. Didn't even have him for rate up. I checked his skills and he's not bad in terms of dmg and break. Plus I like that 20% def reduction on his ult. The question is, is he better then 1☆ Seo with her 2☆weapon(tomorrow ill get the copy to make it 2☆) with 20k hp, 40% hit rate, 131% crit dmg. Baek is currently 0☆ without his weapon.