They both are very different products. If you want to compare similar products, then it would be Collinite 845 and Soft99 Kiwami.
You won't be wrong in choosing any of the products since both are quality brands.
Just to clarify if you go with Fusso, don't use Meguiar's UP since it contains glaze as well. Fusso only bonds well to bare paint. Your Turtle Polishing Compound looks ok to me in the case of Fusso. The only step I would like to add is IPA wipe down before applying Fusso.
I would not suggest you use Meguiar's UC every time. Remember the paint is thin. Be careful using compounds frequently.