Sony MDR-EX71SL
These are on sale on Amazon. I highly recommend them. From my research, people tend to like these guys better than the Koss Plug. I havn't heard the Koss Plug's, so I can't really comment there.
They have a nice tiny protective case, and three silicone sizes to fit your ear. They block out sound moderately well too.
They have great bass, very surprising, not bloated at all. However, the highs can get a bit tinny at times, but I'm used to axioms. The midrange is excellent.
Sometimes if I don't get a good fit (The best way is to reach your other arm over year head and pull up the tip of your ear) they get irritating. However, picking the right size helps a lot too.
