Sorry for the delayed response, this one slipped under my radar...
The S-VHS players, especially the high end ones by JVC, have the ability to take a less-than-perfect tape and make it near-perfect in output.
It has video and audio filters, and upper end ones have an embedded TBC (time base corrector) that uses DNR (digital noise reduction) algorithms to purify the video signal.
The dedicated TBCs (like the DataVideo TBC-1000) is mostly good for stabilizing a tape, it will have zero affect on visual quality (aside from removing motion, side-to-side, up-n-down, jitter, etc ... stuff that is NOT part of the original video signal, but is caused by a bad tape).
Good wires are also important, use Monster if you can, at minimum thick gold plated and insulated. Use RG6 for all coax, not RG59.
Here is a simulated sample of what a JVC can do. This is very close, no exaggeration. Just today, I have been working on a similar project:
BEFORE JVC:
AFTER JVC:
Notice how it elimated that red/blue gamma noise, and then it can soften and/or remove grain. This is especially helpful on old EP/SLP mode VHS tapes.
For the record, I have no JVC stock, I am not a salesman, and I get no kick-back from JVC. But this is a piece of equipment I could not exist without.
