I've been highly recommending Sony's for a long time now, but for my left-at-work pair, I use a MDR-XD200 headset that I paid $18 new 10 years ago. They're nearly indestructible, sound better than most non-Sony sets I've tested them against and when I've got music playing, they block out the world really well. And, most importantly, they're so comfortable that I forget I've got them on...I almost wish they were less comfortable so I didn't have them ripped off my head when I stand up without remembering to take them off first.

I use a more expensive pair of Sony's at home where there's less chance they'll be damaged.