I've used a few of the popular WP themes out there in the past (won't name them by name but they're very popular) and they were nothing but headaches. Coding was a mess. Support was less than par. Sites loaded slowly. Design wasn't as great as I'd thought it would be.
I'm using True Pixel now and completely love it. It's fast, it does everything easily, and the support has been great. It's an intuitive theme with none of the headaches of other themes such as hooks and whatever steep learning curves other themes have. And it looks great on mobile.
This theme with a few plugins has made my site look very professional and load fast.