[wlesieutre]

Linked this in a related discussion yesterday, he has a page specifically for this question: https://www.brandonsanderson.com/where-do-i-start/

"The Cosmere" is his overarching fantasy universe, with The Stormlight Archive as its big fantasy epic (beginning with The Way of Kings). That series has references to his other fantasy work, including his other big series (Mistborn), but you don't necessarily need to have read anything else first. I think there are 4 books now with 10 planned, I haven't read the latest one yet but I enjoyed the first three.

It's been a couple of years but I remember really liking The Emperor's Soul, and it's a $5 ebook novella so you're not investing too much time or money to check it out. DRM free from Kobo, not sure if that's the case via Amazon/Kindle.