Specifically, for those two models, the 7800 is probably superior to the 9500. But that also assumes all other things are equal: head condition, alignment, usage hours, etc. And the latter matters more than the former. Both 7800 and 9500 cold be inferior to others simply do to condition alone. I have a pair of SR-V101 left (for sale in the marketplace) that could surely give some other JVCs a heated competition. If SP, not EP due to lesser alignment, then I have a quality JVC LSI combo that could potentially squash all of them, do to the transport build quality.
Are you confused yet?
I know, sometimes you ask a seemingly easy question, and get the complex accurate answer.