Here is my favourite themes developers collection.
Each of this websites have a great catalogue of themes that I personally use for a lot of works, so I personally know that each of this websites will give you great results.
Theme Forest is a great collections of professionale themes. Always I try to buy from theme forest becasue the quality of the themes are excellent. You can find themes of every kind at a fair price.
A good collection of freemium/paid themes. Really easy to use, and with a great Design, they are the perfect themes for who start a new wordpress experience.
One of the most professionale and SEO ready themes. I consider the studiopress team the best wordpress themes developer team due to many factors.
Impressive with the most amazing design and great plugins. It’s a great themes collections perfect for some particular kind of projects.
I have been a Woo Themes lover for long, and I still love the Free Woo commerce plugin as one of the best solutions in my opinion to create an ecommerce website, even if lately I prefer to buy a theme from Theme Forest woo commerce ready, so I can integrate the free plugin with better designed themes.