Personally I love Samsung One UI, because it provides the right balance of useful features for an Android skin.
For example:
1) Smartstay
2) Scrolling screen capture
3) Theme Park
4) Font selection
5) Screen Recorder
6) Ability to set the lockscreen to any video(via the Samsung Gallery app)
7) Customizable Always-On-Display
8) Blue Light filter
I also have a Pixel 3(had a Pixel 4, traded it in for a Galaxy S20). I have come to find Stock Android lacking in
useful features(i.e. flat out boring) compared to Samsung One UI.
In fact Stock Android eventually adopts some of the features from other Android skins years later
Stock Android is nice, just doesn't offer enough value for me to date.
The only features I miss from my Pixel are Ambient Display, the new Google Voice Recorder app w/ transcribe and Call Screening(which
arguably should be an Android OS instead of an exclusive Pixel feature in my opinion).
Bottom line?
When it comes to Android overall, although not perfect, Samsung flagship phones are the best to date in my opinion.
But like many things in life, this is a subjective thing.