They straddle between casual and reference. You really can't get solid reference/monitor in a closed phone. For open phones,a good starter reference would be the AKG701, but that is difficult to drive and anemic down low. For true ref tt seems you have to move up to things like the Senn HD800/Beyer T1 to get near ruler flat frequency.

For monitor use, and by that term I'm talking about actual pro-audio where isolation is a plus, really the high end custom IEM (IEM = in ear monitor) is where it's at.

But as with most things, be careful what you wish for. A true reference can be boring unless you're using well mastered source material. Most pop/rock/electronica doesn't fall into that category, and with that notion it's best to listen to a bunch of cans and let your ears be your guide.

The components in my chain cater to my preferences. It's not the most uber-accurate, but for my purposes emotional engagement is key - it let's me tune out from my environment and focus on my work.

AKG K701s are not difficult to drive - 64 ohm is not that much - but they leak sound so bad, I don't think I'd ever recommend anyone using those in an office (unless you want to hear everything around you or listen to music at deafening volume in which case everyone around you is forced to listen to it as well).

JH-16 Pro Customs... nothing else, all day, every day!

Wow, I didn't even know they made custom IEMs, vs. just custom earmolds for the standard Etymotics, Shure, UE, etc. IEMs. This is like a whole additional level of audio geekery :)

You're asking the wrong question. Nearly all "audiophile-class" headphones are used for what most would consider casual listening. The distinction you want is "fun" vs. "neutral," and depending on who you ask you'll get very different answers on preferences.