Comparison Between Sync Engines

Hey! Has anyone read a good comparison between sync engines?

I'm interested by them as they can shave off a lot of manual work, but I'm also skeptical of how they handle conflicts because the demos only show the happy path.

I'm mostly focused on JavaScript sync engines, but the question is applicable to other language ecosystems as well.

What are your thoughts on the options? If you have any experience with a sync engine, how was it?