What do you want your theme to do? What purpose are you using it for? Just blogging or something else?
StudioPress themes for me. Heck, on there support forum they have recommended professional designers who can create 1 off custom themes that run off the genesis framework that will blow peoples mind. (Of course you need to have the money to hire them) There themes in there database are good ones that yourself can customize a lot. Remember when you look for a "premium" theme, you need to make sure it's coded well or you'll increase the chances of getting your blog hacked into. There are other factors to getting hacked but poor coding in the theme is one of the way's.
I really love the themes from oQey Themes. These are easy to use and original. I use them often for my websites. The oQey team has always some flexible and affordable new themes. I don't think that the price is too high for their product, as it is really qualitative and the team was responsive every time I needed their help.
If you go for budget, I'd recommend you Elegant Themes. You get almost 70+ themes for the price of only $39.00