Generally speaking, Org Mode is the only thing that's really missing in Vim in comparison I think. I've been using Vim Wiki but have been told it's not really comparable.

Put it the other way, what's the one thing that would be better if you did move to Vim?

Or in another way as well, what about Spacemacs/Doom would make you want to move away from it?

Performance and removing the Emacs keybinding layer that I think complicates the way I use the tool. But mostly performance.