I can't compare to the JVC since I never owned it, but I did own both the AD700 and CAL. the AD700 has incredible soundstage, but as you mentioned, it does have very light bass. The CAL is one of my all time favorite headphones and I definitely enjoyed it much more than I did the AD700s, and did not find them uncomfortable at all. Both headphones can be worn comfortably for many hours.
I think the biggest thing you need to ask yourself is whether or not you need isolation and what type of music you listen to. The AD700s are more detailed and have better mids/highs which would probably make it better for classical/jazz, while the CAL are warmer headphones and are more suited towards pop/rnb/edm. I personally prefer the CAL though, as I really enjoyed its sound signature and found the AD700s to be one of the lightest bass of all the headphones I've owned so far (you can check my profile to see everything I've owned).