Obsidian vs. org-mode is pretty much like VScode vs. emacs. Obsidian has a more immediately accessible interface and a big community of plugins, but the available plugins tend to operate at a higher level of abstraction. Obsidian is also document-centric rather than outline-centric, although org-mode can be used either way. Calendaring isn't native in Obsidian and there is no org-agenda, but you can cobble together something similar with queries depending on your needs. Functionally, there's no real reason to switch from org-mode, but if you primarily want Roam-like features and find org-roam too confusing or awkward, you might consider it.