The verdict
If your team builds many similar sales, pitch or investor decks and has nobody to police the layout, pick Beautiful.ai. The slides keep themselves tidy and the theme holds the brand.
If you also need social images, ads and one-pagers, or you want to start free, pick Canva. One tool covers the visual work of a small team, and the brand kit keeps output consistent.
For most small B2B teams I'd pick Canva. It does decks well enough, costs nothing to try, and covers everything else you will need. Choose Beautiful.ai when decks are the main output and consistency matters more than freedom.