I've enjoyed Stormlight so far but Mistborn (especially the Wax and Wayne series) beats it by a huge margin. Stormlight I feel will bring more threads of the Cosmere together and will be much more of an Epic story but Mistborn is just a good tale with some very good cosmere twists.
Another vote for leaving Stormlight. Mistborn would be my vote as a starting point (all of it), then Elantris and Warbreaker then novellas then Stormlight.