I've had the Sennheiser HD700 for many many years. I've tried changing them with many other headphones, even selling them and by the end of the week i have bought HD700 back again
They really have been my go to headphones and i feel they are almost perfect. Super comfortable but the sound could be more "fun". I am primarily using them for gaming but i also listen to music a bit.
I've listened to HD800S and wasn't blown away by them but they are amazingly comfortable just as HD700 is. Then i got to try the Denon 9200 after seeing a reviewer on youtube got emotional after listening to them. I was blown away as well cause its closed back but it feels open back and is very comfortable. Even the sales guy in the store used them as his primary driver. But the Denon 9200 is either loved or hated when i check forums about them. I guess the HD800s is the safest upgrade but want to hear opinions from the rest. Could very well be i am using the endgame of headphones with the HD700's, i don't know.

I've listened to HD800S and wasn't blown away by them but they are amazingly comfortable just as HD700 is. Then i got to try the Denon 9200 after seeing a reviewer on youtube got emotional after listening to them. I was blown away as well cause its closed back but it feels open back and is very comfortable. Even the sales guy in the store used them as his primary driver. But the Denon 9200 is either loved or hated when i check forums about them. I guess the HD800s is the safest upgrade but want to hear opinions from the rest. Could very well be i am using the endgame of headphones with the HD700's, i don't know.