If you are looking for a free WordPress theme, then WordPress.org is the best place to start your search. With 4800+ free themes, it is the largest collection of free WordPress themes.
MOJO Marketplace is a large marketplace for WordPress themes, plugins, and services. They have more than 7900 items on sale, including 900+ premium themes. You’ll also find their WordPress services offered by top WordPress hosting companies like Bluehost.
Themeforest is part of Envato family, a large network of design, graphics, audio, and video marketplace. Themeforest offers a large collection of premium WordPress themes neatly organized in categories and easily searchable.
Elegant Themes is one of the oldest and most well-known WordPress theme shops. Elegant Themes offers premium WordPress themes, plugins, and one of the best drag and drop page builder in the market, The Divi Builder.
CSSIgniter offers a large collection of premium WordPress themes for almost any kind of website. With more than 80 premium themes, CSSIgniter is catering the needs of WordPress developers and website owners since 2010.