Here is my list in no particular order, but first…
Jason Schuller (love this guy’s work)
- Elegant Designs
- Graph Paper Press
- Shaken & Stirred Web
- The Theme Foundry
Of course, they all differ on their back-end design framework and approach. My advice, whichever one you pick, pick for the long haul as it may be hard to switch away from one theme to another.