Things to keep in mind: The difference between S-video and composite video is almost non-existent. There is an extremely small difference in image quality between the two, but it is far smaller than what one would expect. I'm not sure how much you are intending to use a technology which hasn't been manufactured for what... a decade? It just doesn't make a lot of sense to invest in old technology over and over and over when we live in a HD world which is surrounded entirely by HDMI. Support for 4K should be a requirement for any purchases made.
If you are entirely determined to walk down this path, then that's up to you, and my post isn't meant to offend, but I've seen a fairly long list of my client's want to integrate old technology into their setups, only to realize that they almost never use that old technology anymore. Not when there are tons of options in the digital world which make it fully accessible at the same, or better quality. Get a video capture device and digitize everything and call it all done. Get new HD digital copies of any movies for next to nothing. It's all possible these days. Obviously, old home movies that need to be transferred are some work, but it really should be backed up into a digital format anyway.