This is a simple question, but longer answer.
The reason to own a good deck isn't just TBC, especially when discussing Panasonic AG-1980. It's the transport, VHS-C non-eating, tracking, transport stability, etc. The best units just also have the TBC. But it's everything.
The field TBC in the Panasonic is strong, not ES10/15 strong, but also not crippled like ES10/15 (anti-copy, both true and false detections), nor other quality hit issues of ES10/15. But AG-1980 lacks non-TBC frame sync, and is expected to use actual frame sync TBC after the deck.
ES10/15 is best for anti-tearing, not used as general TBC, because it both harms and improves quality. In anti-tearing situations, the net results is better. But when tape good, ES10/15 net result is worse than just a good frame TBC.
First TBC in workflow wins. You cannot stack like TBCs.
So line>line is the 1st line (VCR), not latter ES10/15.
But frame+line TBC is fine, those are not like. Frame cleans signal, line cleans visuals.
If you want to use the minimalist TBC(ish) of a ES10/15 -- noting a truer TBC(ish) is ES10/15+DVK, for 99% efficacy, though still with drawbacks -- then you can just use a quality non-TBC JVC. There's really no non-TBC Panasonic worth anything. But it should be a better model, in minty condition. The 4800, the 5902, 3600, 3800, etc.
All as s-video, yes.
Anyway, to directly answer the a/b option, I'd punt, neither. I'd rather do AG-1980 or SR-V10-based EOLs, TBC off, to the ES10/15. But I also own multiple actual TBCs, so realistically I'd do neither.
Answered? Or more questions?
