Because this is in the "Full-Size" headphone thread, I assume it has to be 'Over The Ear'?
There's something I'd like you to answer.
Is Semi-Open headphones ok? they isolate fine at low volumes to where you can hear not only your music but also your surroundings (great for going out and about and want to be aware of your surroundings.)
You MIGHT wanna look into the M50's Big Brother, the PRO700MK2s, now I've seen a lot of threads/reviews saying these are subwoofers on your ears... that's an EXTREME exaggeration. However the bass extends Far lower than the M50s, and has a much more satisfying punch. Again, do not think these are bassy, they're just very solid. Also be aware that the mids are statistically recessed, but by ear, sound just fine, clean also quite forward. The treble is loud, and sometimes bright, but has NEVER been sharp or painful. WARNING: The PRO700MK2s come with insanely terrible earpads and i would recommend replacing them ASAP. The clamping force is also known to be insane. (personally, i love how it feels like a hippo clamping down on my skull, trying to pop it. very snug and secure.) Also they're super durable like super durable... uhh... yeah... good luck breaking them... like... ever...
Another Headphone if your ok with Semi-Open would be the Superlux HD681 EVO, i got these recently and love the open spacious sound that i could never get with my PRO700MK2s. However the bass is way too loose and bloated sounding in the upper bass. (Fix: <Will edit in link to a thread i have not made yet about my mod that fixes this issue, at a later date...>) After my mod, it sounds much closer to how I like my sound (aka Mostly Balanced but with a powerful feel) and for the most part these are neutral, not super flat, but more than good enough. now for the cons on the sound... after my mod, the sound is decently tight, they are in no way as tight as the M50s or the PRO700MK2s, but good enough... Now for why I think you should really go for these, despite being a couple steps behind the M50s and PRO700MK2s... they only $41 USD here, instead of the ~$165 the PRO700MK2s are here. Great for saving on getting portable amp (i'd recommend the FiiO E12, does not color the sound, and PLENTY of power.)
Another Headphone to look at is the SoundMagic's HP150, I cannot say too much with these as I have not had extensive time with these. But the sound is good, clear. Fairly neutral. but they will cost you your full budget of $200.
I hope I helped.