MezzI have the DT880 and a friend just bought the AKG. It depends on your preferences. The 880 are a lot more neutral, in that they don't enhance certain frequencies of the music, bass, highs etc. I imagine they sound pretty much like the music was recorded, perhaps a little weak on the bass side. The AKG are more dynamic, with more heavy bass without being overly bassy like certain Sennheisers can be or, if we go to the extremes, SMS and Beats.
They're both great, but also very different. You'd have to try them yourself to find out which are the best for you.
MezzThe Beyerdynamic are more "fun" to listen to, escecially praised with Rock. The K7XX are a little bit more analytical, so better as a studio headphone, but with 3 db more bass than a normal studio setup. If you want to listen to great mixes as the studio intended, but a little bass-heavier (as much as an open setup can provide) get the K7XX. They also have the bigger soundstage (although not as big as the K501, which are my favourite). So, for Gaming the K7XX is also preferable.
If you want to listen to relax, mostly Rock, and for long hours, get the DT880. Both are the most comfortable headphones i have ever used. Also note, the K7XX can be successfully driven by an iPhone / iPod without an amp (67 Ohms) WITHOUT losing "detail", "tight bass" or "definition" (which all are audiophile myths - at least for amplification), although you will not be able to crank them up very loud.
Ultimately, it is a personal preference, they are both considered top products in their class and price range, and both Massdrops are worth it.
I would not recommend the DT880s for mobile use without an Amplifier. (Or a DAC / AMP combo if you do not use an iOS device). If you drive them on the edge of your mobile device it *may* lead to distortion.
JPHKYou must be kidding right. I think your ranking could be right for the earlier 70X series. K7xx though, is extremely, extremely comfy. It is lightweight, spreads out weight very evenly, and the headband doesn't have a bump. I have HD650, K7xx, M50, and K7xx is by far the most comfortable pair. I barely feel them on my head, and based on many reviews I think most other owners would agree. So even if DT880 is extremely comfortable, I think you are misrepresenting them by saying "Comfort: DT880 > K7XX".
JPHKMeh, I'm enjoying my K7XX, but their sound quality isn't better than the DT880. Maybe an Austrian version would be better, but I've noticed issues with these PRC manufactured cans.. especially when comparing to something like the DT880
growl3rI have them both and feel the same about them as you do. I've listened the K7xx for quite a bit lately and I find that its treble roll-off makes for a kinda polite sounding headphone.
I'm keeping them both, though :)