Having both an HE90 & HE60 and an HEV90, and extensively used the OO2, I would say following:
HE60's = most comfortable, classic seenheiser vise-like tight seal. I have a smaller-type head and I find this to be comfortable.
HE90's = once settled right, comfortable, but more delicate on the head.
Also more delicate to handle. The huge drivers and greater weight make them susceptible to 'floppiness' if handles from one earcup. I wouldn't call this product built poorly, I would say however, that it requires kid gloves (as anything in this price range would), and over time the headband and possibly the screws if handled poorly will wear out.
OO2 - Strange fit for me. Sound seemed 'tweakable' dependant upon fit, and I generally don't like that aspect of a phone. I want the most natural and single position it wants to be on my head. But, this headphone, more than the others, seems to 'change', not necessarily benefit, from different amps. Heard it out of a KGSS, Blue Hawaii, HEV90, 007t, and found that, the HEV90 made it sound the worst. The rest had varying degrees of virtue.
I am soon to get a maxxed out ES-1. We'll see how that sounds
It'll have 3 plugs, HE90, HE60, OO2; Handy for 3 people listening sessions, oh, and comparisons too.