By far, I am most excited about Recurring Meetings and Recurring Meeting Notes. We do a weekly "Level 10" meeting in my org, and being able to work through an agenda, take notes, assign action items to a To Do list, and then review those in the following week is crucial.
I would say: OneNote is most of all a tool to take notes and especially keep them good structured. Loop is really strong as a collaboration tool. It has a lot different functionalities like making notes, tasks, tables and much more and can be connected to a lot of ms apps.
