Audio-Technica ATH-MSR7
Still have a love-hate relationship with these. Hate the unbearably creaky plastic and the midrange harshness that becomes too much with some tracks. Love their airy, clean and effortless sound that doesn't sacrifice bass quality as well. Constantly oscillating between considering to get rid of them and falling back in love with everything they do.
Audio-Technica ATH-M40x
These are the headphones that I use at work. They feel somewhat muddy to me, perhaps due to the upper-bass hump or bass distortion. Still pretty dynamic and natural sounding, especially at higher volumes. Probably shouldn't have skimped on money and bought M50x instead.
Audio-Technica ATH-A1000Z
Bought them almost on impulse when I was in Japan. To my dismay, after some time I've spent with them I still can't hear a single thing they would do better than MSR7. The mids sound congested, the bass is not nuanced, the treble is "grainy", the soundstage is non-existent, and there's some peak in the upper mids that makes vocals really fatiguing to me. They're also very sensitive to how they seal on your head, so glasses are a no-no unless you want the bass to get completely ruined. The only thing I thought was good about them was their solid build (they certainly don't feel cheap like MSR7 do), but after a couple of months one of the cups became loose due to threadlocker on the screw failing to do its job, so the only apparent upside went out the window. There's some hope that they'll blossom with a better amp, but I doubt that FiiO E10K that I'm currently using is that bad at driving them.
The favorite one? Obviously, MSR7 for now, but I'm on the lookout for something that will finally make me feel satisfied with what I hear.