What book should I start with if I'd like to get begin reading his stuff?

Either start with Mistborn #1: The Final Empire or The Stormlight Archive #1: The Way of Kings. They are his main series, and generally regarded as his best stuff. Would probably recommend Mistborn as it's been finished, and the mainline story is only 3 books.

> They are his main series, and generally regarded as his best stuff.

I think Elantris is his best. It's just that there's less of it (one book) than there is of the big series.

Elantris is great, but the end of the books is basically a gaping gap. Not entirely, but a bit like the story was cut off in the middle.

Others haven't said so but maybe you should try Warbreaker as it's the "most" standalone book of the Cosmere saga. It's the "most" in the sense that there are still subtle references to other works but they are very minor and you can totally enjoy it without reading the rest of them first. In fact, once you read Warbreaker you can see some connections with it later on the Stormlight Archive

He actually has a section on his website with suggestions for where to start.

https://www.brandonsanderson.com/where-do-i-start/

The emperor’s soul is a short novella, and is excellent. The quality to time commitment ratio is fantastic.

I second this choice. Legion is another short story novella that is really fun. My favorite Sanderson series so far is the Skyward series, for which I highly recommend the audio books. The narrator is amazing.

A friend suggested I buy the entire Mistborn series as one ebook. That worked for me.

Way of Kings