Csync is preferred when available, but there are some consoles (PSX, PS2, 1CHIP-03 SNES, some N64s depending on the RGB mod) that only output luma sync, which I don’t believe makes any appreciable difference in picture quality. The main thing is to avoid sync-on-composite, which is the one that can really result in artifacting.
Note that stores will offer Csync cables for consoles not supporting Csync, which means there’s an added sync stripper inside the cable. The OSSC supports all three sync types, so there’s no benefit to these over the regular ones passing the original sync signal from the console.
For my part, I’ve gotten all my cables from retrogamingcables.co.uk (funnily enough, for a Canadian it actually ends up being cheaper to get them from the UK than the US), and I haven’t seen any of the issues rebrove mentioned.