You know, it almost changes every time I (re)read one, but I'd probably have to land on Oathbringer; it hit me really hard (in a good way) emotionally when I got to the end both times I've read it so far.
Hello, I'm TLhikan. I started reading the Cosmere last year and got pretty hooked; I'm caught up on everything except White Sands 2 and 3, and am just this year starting to reread everything.