Roam Resaearch is a powerful app. Last year, I used Roam as my primary note taking app. I am grateful to Roam to award me a one-year scholarship. As my scholarship period comes to an end, I have a few reflections that have made me swtich to Obsidian.
My main problem with Roam was its speed. It is a great app, but takes a while to launch, espeically on mobile. That is not optimal for taking quick notes.
While Roam graciously offered me a scholarship for year one, I do think its price is quite high for my use case. I beleive a free iteration of Obsidian will suffice for my D.Phil.
There are other features to Obsidian, like ownership of your notes, optional publish to blog, and custom plugins, but so far I have not had a chance to dig deep into obsidian features. However I do appreciate the potential power of Obsidian thanks to its open doors for custom plugins.
Another neat feature of Obsidian is that you are not compelled to write bullet points. In Roam, the fundamental units are bullet points. That is good, and you can have those same features in Obsidian, but the latter alllows for more styles of notes, which is a handy feature to have.
To wrap, I think Roam is a great app. It is well built and brings an innovation in note taking. However it does have some downsides, which is why I am currently switching to try out Obsidian.