DT770 has the best isolation I have heard.
I have these and used them with my front panel audio for some time. I eventually got a DAC because I was getting some interference noise. They are very comfortable for long periods, have a wide-open soundstage, and sound excellent for games and music. They are also great at isolating sounds, as I can't hear my aircon, pc, or neighbors while wearing them. At the time I had noisy roommates, but if I were buying now I'd get something open-backed instead. My ears get rather hot after awhile.