As far as I’m concerned it all depends on what sync the console itself outputs, and also what you’re looking to connect it too. Csync is considered to produce the best quality, then Luma, then composite video sync. Generally, sync strippers are only really required for specific display configurations like PVM’s etc.
I’m currently using a gscartsw with an OSSC, I have the sync stripper set to “on” on the gscartsw. Here are the RGB SCART cables from RetroGamingCables I’ve tested so far and they all work perfectly:
Mega Drive 1 PAL & JAP NTSC – Csync
PS1 NTSC – Luma Sync
SNES PAL – Luma Sync
Hope that helps