I own these two cans and hook them up to Musical Fidelity X-CAN v3 Amps. I use one for work and one at home when the kids are asleep. I don't have much experience with the other makes except the Grados, which I remember thinking that they had terrific sound; a little bass heavy and had less space and imaging. Also, there were not nearly as comfortable for extended listening.
They are both great sets. Both have very natural, tight bass, the type where you can distinguish specific bass pitches with ease. Both are dynamic and bring out subtleties within each performance. Both are very neutral in character and very revealing, especially the AKG. I had the Senny first and wanted to do and A/B comparison with the AKG. I wound up keeping both of them as each has specific strengths depending on what type of music you like.
To me, the AKG is quite a bit more detailed and up front; it is great with rock, pop and soul. Folk vocals, male and female, are natural without undue high and low extension. These sound like the more sensitive cans so they are a good choice with little or no additional amplification. These were also very comfortable to wear and non-fatiguing for long listening sessions.
The Senny has a more relaxed character where the each instrument can be heard and placed. I find that the music has more layers with these cans yet the whole presentation remains cohesive and gripping. These were made for jazz, classical and orchestral music. These do though, sound best with a good amp.
All music sounds great on both these sets, I just noted where a type of genre plays to the strength of either can.
Either of these choices is a home run. Good luck.