Definently see your point , I also have the pixel 3a , did have the 3xl until traded in for my note 10+ ....s10+ i also have which is a solid phone .
Right now I'm actually content with the note 10+/1+7pro/pix3a but I'm a sucker for new devices and I do like pixel phones also .
Pixel 4 is tempting, at least for the camera and the software + updates.
Having said that, I've always felt like a bit of a guinea pig on Pixels because we are basically beta testing the cutting edge of Android. The new and unproven face ID doesn't help. And while I used to despise Samsung for the bloat and custom UI, they have done really well with One UI, the gestures, dark mode, so far they have been quite good with updates, Android 10 beta is already out, etc. Also, the S10+ worked perfect out of the box, fully supporting all carrier features such as VoLTE and wifi calling without a single call to my carrier. My S10+ has been a rock solid, dependable workhorse from Day 1.
To move to a Pixel 4, I would also have to give up a headphone jack, FM radio, edge apps / lighting, sd card, 2GB of Ram, 2 cameras, dual messenger capability, Samsung DeX, power sharing, screen size and dpi, up to 1/3 battery life reduction, secure apps and folder, display blue light filter, among other things. Those are pretty big shoes to fill for any phone, but to pay as much as I did for the S10+ not to mention the resell hit I'll take on it - very, very difficult to justify the switch to a Pixel 4 IMO.
And on top of all that, I've taken some really great photos and videos on my S10+ as well, so even the camera argument is a difficult one.