I use and love both of them. Both sell brand name, gently used clothing and accessories, their shipping is fast and searching the sites is so simple. Twice sells only women’s clothing and ThredUp sells women’s and children’s.
If you want to go ahead and sign up and you use this ThredUp link and this Twice link, we’ll both get a credit to the sites! Everything I’ve purchased has fit well, though I only buy brands that I know the sizing fits me, and has been the exact quality that was listed on the site.
Oh, any by the way, neither of them know about me, I’m just sharing because I’ve had great experiences with both!