Does your bathroom sink or toilet scratch easily?
Ceramic is stronger and more durable than glass... At the end of the day all materials can scratch, dent, break etc.
If I get an S10+ (and I'm leaning towards it), I'd get a ceramic back for sure. I really like the ceramic white. I don't think it'll show as many fingerprints as the black.
BTW, the higher-end Apple Watches are made of ceramic because it's more durable.
Scratch resistant, yes, but significantly more brittle and prone to breakage when dropped.