When I got my s10 plus I almost immediately switched over to nova launcher. This is not because OneUI is a bad launcher. It is in fact quite snappy and responsive and it would've been my default launcher if not for a few features that nova launcher has that I find important.
1) Firstly, due to the high position of the power button, an option for double tap to sleep on the home screen would be a welcome addition
2) The entire philosophy of OneUI was to make one handed usage easier. However if one opens a folder on the home screen, it takes up the whole screen and the apps are on top. This takes away the seamlessness of the experience and I would personally love an option to reduce the size of an open folder.
2nd suggestion is a great one. And yes it takes away the philosophy of OneUI. Samsung must try to improve very few minute things in OneUI to make it really the perfect OS. But still it lacks in sheer performance grounds, sad!