Having used a couple sets of h6mk2s, the h7, and the h9 (but not h9i) I have some personal opinions. Here is a brief overview.

The h6s are lightest and sound the best, especially in a quiet space. The H7s with a good quality cable are similar to the h6s but not quite as good space and detail but only slightly less so. With Bluetooth they are quieter and not as spacious but only slightly less so. The H9s don't sound nearly as "complete" without the ANC on, it is more than just noise cancelling I think. The sound is pleasant but not as articulate as the other two either with Bluetooth or wired. Great sound for background music, not as good as the other two for serious listening sessions. The pads on the h9s are thickest. The ANC on the h9s (not 9i) is good at decreasing motor sounds from engines and fans and wheels, etc. The h9s are not great at removing voices but much better than the passive isolation from the H6 or 7s. The h3 and e4 are both better for voice isolation.

I wanted to listen to a new album really closely recently while on a commuter train, brought the H6s with me but was so distracted by outside noise I couldn't listen. Next day h9s, much more enjoyable on the train. Came home, quiet, h6s, fantastic!

Does that help? Save for the h9 or h9i for your situation is my personal opinion.

I am very happy with H6 2ndgen and so is my colleague that just bought a pair recently. They’re still out there, even at B&O retailers. I personally would recommend a wired headphone at all times.

Hi,

I currently work in open office space, and I have been using H6 (1 and 2), H7, H9 and H9i here.

 

If I were to buy a pair for office use, I would chose H6. No need for wireless when sitting at a desk.

I use them with an amp, so if I play loud there is some leakage of sound.

H6 is the most comfortable of al the H`s.

And you basically get them thrown after you nowadays.