If there is an important question before buying or comparing headphones its this one !!!

All sound consideration appart It first depends in fact what you plan to do with your headphones.
For exemple closed cans will be perfect for a recording studio to avoid sound leakage during recording that can be recorded by very sensitive condenser mics.

In the same way for a drummer closed cans provides a better isolation and are necessary.

Globaly closed headphones are the way to go in noisy environment like train , metro, plane, street, club, outside …..

Even in a recent building not very isolated noises >40 db can be an issue when listening with very open headphones.

Open headphones in the contrary are the path to take in quiet environment. They are generaly used in the studio during mixing session as a complementary tool of monitoring speakers end also for some mastering applications.
For use at home they generally provide better soundstage, stereo palcement and comfort compared with closed cans.

In progress:

On other side we have open headphones :

– Generaly more confortable over long listening sessions
– Globaly more large soundstage