I spent some time researching this topic over at
/r/audiophile,
/r/headphones and head-fi (make sure to check out this
definitive guide).
Through my research, audiophiles have made it clear to me that the heuristic to use when buying your primary headphones is to use the price/performance ratio. Brands like Monster Beats and Bose are way too overpriced for what they deliver, and hence should be avoided.
Another tip to keep in mind: the best way to know which headphone is a good fit for your needs is to
try them on. Sadly, our return policies here in Lebanon aren't always lax enough for that.
A quick heads-up: high impedance headphones will require a good external amplifier to drive them, you'll also need to invest in a DAC if you want to monitor your computer audio.
I went with a
Sony MDR-V6, mainly because it was on sale on Amazon ($50!). Its design has been proven to work for the past 20 years. It seems that I'll have to change the ear-pads every couple of years, which isn't a big deal. At 63 ohms, they don't really need an external amplifier to drive them, which means i'll save on a couple of hundred dollars.
One last thing: two good ways to narrow your choices down. If you need to buy the headphones from Lebanon, you won't have that many quality choices so the process will be straightforward. Second, decide which
type of headphone you are looking for depending on your needs (for example, if you are in a busy environment, nothing beats in-ear monitors to isolate everything out).
Good luck!