Excerpt: As far as affordable on-ear headphones go, it may seem iGrados are the de facto choice. Not so; their open-back design means they leak noise badly, making them an inconsiderate choice for commuters. That's where closed-back headphones like the Sennheiser HD 218s come in. They may lack the spaciousness of open models, but at least you won't fall out with a stranger on the train.
Pros: Leak minimal noise, weighty, clear delivery
Cons: Lack the spaciousness of open headphones, bit more detail and tighter bass would be nice