Well I'm torn between these headphones
Audio-Technica ATH-R70x Open-back Dynamic Reference Headphone and the AKG's, I could use some help choosing.
The AKG's are very good, I have the K701, which are very similar to the K712. The K712 have more bass response and a removable cable.
If you want to record vocals, I would prefer a closed design (feedback! or the mic records the leckage from the headphones).
Headphones for monitoring purposes are different than headphones for mixing.
I own the K240s and the K141 too and as much as I liked them in the past, the newer designs are much better. The 240 and 141 were designed in the 70s and much has improved in headphone-design since then.
Although I like the definition of the K701, the headphones I use the most are not that popular among bass players or in studios, but among dj's: the AKG K267 Tiesto.
These are closed headphones with a special feature (some Beyerdynamic headphones offer a similar feature): they have a kind of bass-reflex system that you can change. It's not an EQ, it works in a mechanical way. You can change the settings between Studio (neutral), stage (more bass) and club (even more bass).
I love that feature. If you want to have fun just playing bass and don't go to very high volumes, you simply use the club-setting. But if you're just listening to music or mix, you use the studio-setting.
Another feature I like: it has removable cables, just one cable, but you can connect it to the left or the right capsule.
Very comfortable, if you don't want to fight with the cable all the time.