Any theme which has a decent loading speed (although it doesn't matter unless it shows a time out) along with a good navigation. I think its good.
Just make sure those elegant designs do not compromise your user usability and experience. I'd rather go for simplicity and speed than elegance and usability nightmare.
Divi is fine with SEO. I've optimized at least 15-20 sites for clients that have used Divi and no problems with SEO. It really comes down to how you build it -- a lot of my clients' sites were graphically intense (ie: full screen homepage animated slider) that slowed it down, not Divi itself. However, Divi does use other plugins like page builders that put additional load on your WP install. I think you should be fine though. Just make sure you're always using a cache plugin either way, and always serving images from a CDN. My setup is a bit more complex, I use CloudFlare, Litespeed Cache and Sirv for images. Jetpack is a good all-in-one though, same with Autoptimize.