Obsidian:
The interface is very confusing, IMO. Very difficult to get the hang of.
I find the editing experience awful with the Preview mode, where the markdown syntax keeps popping up. I don't care about markdown, full WYSIWYG is far better.
IMO Obsidian is stuck with the markdown format and files. They are trapped along with their community, some of whom are extremists from the markdown file, even though it actually has far more drawbacks than benefits to build an entire PKM program on it.

SiYuan is so pleasant to work with. All the opposite of Obsidian for me. And it is great out of the box, no need to manage a tons of plugins. What a relief.

For information, a new feature has been implemented for this need in SiYuan 3.8.3 (which will be released soon): context filter.

Thank you to the developers!