If what you have in your notion is mostly ideas, concepts, and thoughts, then Obsidian is a great choice. It is not as great for storing facts, because of the lack of something resembling Notion's robust database system.

So I use both: Obsidian for ideas, beliefs, concepts, explanations, class notes, etc. Notion for Goals, freelance client project info, job hunt tracking, to watch/read lists, images and links for internet arguments, plans for video games, travel plans, technical solutions, exercise and practice routines.