The verdict
If you sell by the hour and cannot say which clients and projects make money, pick Clockify. If your team already works in Notion and wants agents and meeting notes next to its pages and databases, pick Notion AI.
The two do not compete, so the decision is about your biggest gap. For a small service business, I would put time tracking first, because under-billing costs real money. Notion AI only makes sense on top of an existing Notion workspace, and it now comes with the Business and Enterprise plans rather than as a separate add-on. If you only want a meeting recorder, a dedicated tool may be simpler.