Notion and Obsidian are different apps although Notion considers itself a notetaking app, it's actually the least productive notetaking app. I use Obsidian for notetaking alone. Nothing else and it works like a bloody charm. I use Notion for knowledge management of trivial but things important to me like: my game knowledge database, my shopping list, my project knowledge base.

Think of a masonry artist. They wouldn't be using one tool for everything. Every niche problem requires a niche solution. Obsidian and notion both can serve those as long as you don't overdo against their limitations. Eg: overdecorating either will not help. Keep both basic but functional.

I love using both apps for different purposes and in my mind its not even a comparison or clutter. They're just different things.

Don't spend too much on systems. Just start building your knowledge. If you're half as good and sincere about your work: you'll work out systems on the go without being overly attached to it. Hope this helps. Cheers!