Both of these are great Skins over android, each is unique when it comes to feature and design. But my preference would go with OneUI.
After IOS it is considered as the best Skin UI system with fewer bugs and user-friendly.
I actually stopped using other launchers in Android and I'm keeping juste OneUI. It quickly restores your preferences from your Samsung cloud backup when you get a new phone. It's not as smooth as what Apple does with the IPhone but still saves a lot of work.
Once you get used to it, the fate of continuing to use it out of inertia awaits. Fingers don't forget the UI. In that sense, I think that an excellent UI is one that you can use without any discomfort.