Myself, I would go with the note 20U. It has SD card support and the Spen comes with the phone and is built in the phone, not a $40 accessory, $70 if you want the case to hold the Spen. Even if you only use the Spen a little bit, that is even more of a reason to get the note, the Spen is built in to the phone, less of a chance to lose it, plus the note Spen has bluetooth support.
Comes down to if you want access to a built in Spen, and a SD card slot. If you don't want those, then the S21U probably good choice. My father in law has a s21+ and he likes it, but he came from the S7, so anything would have been an improvement over that phone.
Not to mention, there is no indication that samsung is releasing a note 22, they just said in the article that they are going to continue with Spen development, that doesn't mean it's in the form of a note phone. It's samsung, it seems to be a rollercoaster ride all the time, so it's a wait and see game now.