WordPress comes with a simple but powerful theme, usually named after the year it was made. You can customize this theme so it looks like whatever you want. Many professional custom theme designers start with the free theme as the basis and build from there. This website is built on the Twenty Thirteen free theme, with a bit of tweaks to give it, for example, the option to have a full-page template.
However, you might want to skip the cost and effort of custom coding. That’s why I also turn to Elegant Themes for my theme needs. They are my favorite because they have a team of people providing support through their forums. The downside of this approach is that you can’t google for help very well, and the forum search interface is one of the worst I’ve ever seen. But for $39 a year ($89 for developer level) support and theme updates, Elegant Themes is a steal.
Other top-notch theme companies include Theme Trust and Studio Press, who as well as provide themes also provide managed WordPress hosting as Synthesis.