If you're seriously considering switching to Linux, then be aware that nothing you find is going to feel as polished as OS X. Linux developers tend to be more focused on security and under-the-hood improvements while Apple focuses on user experience, plus Apple is a business that can easily afford to hire as many developers as they need while most Linux distros are community-driven.

That said, the Linux user experience has improved dramatically over the past several years, and my recommendation would be openSUSE (what I run), or Ubuntu if you're completely new to Linux.