I value speed and transparency for my headphone listening, and detest a lot of the "extra bass" headphones that seem to be popular now. I love IEMs, although the customs don't fit as well after a few years. My current favorite is the Campfire Audio Andromeda Gold SE.

Senn hd650 is where a lot of us started liking headphones. (TBH, I listened to a pair of those Sennheiser, or Koss?, headphones {the ones with the orange foam against your ear} as a kid from my Dad's McIntosh Pre-amp)

There are much more revealing headphones, especially when paired with good amplifiers. However, great sound can be had with one of the DragonFly dac/amps, and whatever headphone you like (well perhaps now with the HD650)

My current sets (different locations, and different requirements)

Blue Hawaii Special Edition + Stax SR007/Mr Speakers Voce -> extremely revealing, and full range, very comfortable - obviously my favorite
Focal Utopia + Violectric V281 -> no tubes at my work office, I run these with balanced wiring - very nice, a bit heavier than the stats, no complaints
Focal Elegia + CEntrance HiFi M8 XLR -> workstation, need closed headphones here - great for youtube, and some music when I get a chance to sit there.

But, go get lost at Head-Fi, and be sure to check out their for sale threads. There are many great headphones are sold after a short while, when a new "favorite of the month" comes out.