The Koss KSC35s were one of my first WOW cans. I got them around the same time as my SR60s. After receiving them, I promptly threw all supplied headphone/earbuds away.
I used my SR60s for everything. I just liked the sound better.
I liked the SR80s too, but they arrived within a week of my SR325s. I sold the SR60s and SR80s. I now use the KSC35 for my portables. Now, I sometimes get tired of the thumping bass(I use them for five to six hours straight), and miss the uh...clarity of my SR60s.
I like the Grado sound. No, I haven't tried the Senns or Beyers or AKG. My closed cans are Audio Technicas.
That being said, I would go with the SR80s and get the comfy pads too. The Grado pads are the cheapest headphone tweak I know of.