I would start with Notion. Here is how the two compare for a small team's first project.
Notion: A strong starting point when your team wants project notes and tasks together. Begin with a project template and adapt it as you go. Notion Projects
Asana: Gives tasks clear owners and due dates. It is useful when the team wants a defined project workflow from the start. Asana features
Try one real project with your team before deciding which approach fits.