I like the ZMF x Vibro more than the Alpha Dogs, which are "only" $100 less, but that's definitely a preference thing. I do prefer the look of the ZMF's wooden cups though. The regular ZMF is pretty dang good too. I'd totally understand if someone liked them more than their wooden siblings.
I just listened to the Monsters again, and honestly, they're pretty close to the SE530... I got them way back in like 2012
My PortaPros are oddly better-sounding than a lot of other pairs I'd heard. I'd actually rank them above the Bowers and Wilkins P7, well above the V-MODA M100 (Honestly I'd put them close to the bottom of the list), Momentum, T50p (but not above the T51p), Bang and Olufsen H6, and lots more portable headphones for personal enjoyment (not necessarily technicalities; no amount of modding can add that). It could be that I've just gotten used to the sound, but I think they're pretty darn good. I found some weird felt that tamed the brightness, yet also tamed the bass. Over the years, dust has started to get through the holes and into the diaphragm and they have some nasty distortion in the low end, but I'm too scared to send them in for repairs for fear I'll get something that sounds worse.