Generally, open-backed (or “open”, or “open air”) headphones produce higher-quality sound at lower prices than closed-backed (“closed”) headphones, and all of the best-sounding high-end headphones are open.
But you probably shouldn’t buy open headphones. It’s irresponsible to discuss headphone recommendations without emphasizing the important distinction between open and closed, since most people aren’t familiar with how much this matters in practical use.
I bought a great pair of Sennheiser open headphones a long time ago when I did most of my coding at home. But for work in a noisy office they’re no longer ideal. Marco recommends several sets of headphones based on what your needs are.