I'd vote for the AKG K240S: Though it's apparently highly regarded by its owners, there are only ~ four owners on the board yet, as far as I know. So if the K240S is not underrated, it's at least underrepresented. I'd recommend more people to try it, because to my ears it combines many enjoyable virtues of AKG, Beyerdynamic and Grado headphones in a well-designed and not very expensive product - and to my ears it's one of the most neutral headphones on the market, too.
Greetings from Munich!
Manfred / lini