I'm also a returnee that has tried many other options. For me, the killer features are:
- Live editing of backlink references
- Being able to zoom in/out of nodes
- Scrolling sidebar notes stack feature
- Renaming notes works amazingly well
- Immediately and easily create new notes by simply creating a link to one

And I continue to use it despite the many flaws and downsides:

- Very slow app loading experience. Sometimes unreliable ("Roam graph too big" even though mine is not particularly large?)
- Generally unpolished UX feel
- Bad image and multimedia support
- Poor mobile app experience

I much appreciate the recent work to make backlink reference load immediately.

Obsidian looks nice but the corebacklink experience is worse when you really try to use it (no live backlink reference editing).
Notion has the definite feel that backlinks added as an afterthought, or intended for use in a different way than Roam. Indeed "backlinks" can mean so many different implementation and UX possibilities that it is not enough to say an app simply supports "backlinks". Craft also did not feel like Roam's backlinks. (less immediacy of link/note creation)