E-reader recommendations

I'm a high school student who's about to go boarding and has always been an active reader. I have a kindle paperwhite 7 but I haven't used in much since kindle's book selection is very limited in my region. So i'm looking for an e-reader that's around 7"-8". i've been thinking about Kobo sage or libra colour 2, or an e-reader from Boox but i'm not too familiar with their selection. I don't really require the google play store, but i do wish to be able to import PDFs. I'm not really sure which one to choose. My budget is around $200-300 USD. Any recommendations or personal experiences?