I've had reasonably good results digitizing VHSC home video with a composite to HDMI converter/scaler followed by an HDMI capture card. The converter does TBC and deinterlacing and I find the resulting footage to be much more clear and stable than what you get out of a regular composite to USB dongle.

If you have an AVR with composite or s-video in and HDMI out that could also work in place of the converter. In either case you'll downscale the footage back to 640x480 before encoding.

You have to monitor the process start to finish if the tapes are bad, there's nothing around that.

For MiniDV and Digital8 you should straight up get a lossless copy using a cheap Firewire card.