Yeah, I agree. Pixel photos tend to come out better from what I've seen, too. It's one of the greatest (maybe the greatest?) strength of the Pixel.
Coming from a Pixel 4 XL and the Pixel 3 before that, it was definitely something I appreciated. However, it was beginning to feel like that one feature was keeping me hostage and locked to Pixel devices. This is why I'm hoping the S21 is finally the right time to jump ship. If they can finally get their still-photography on par, then I'll happily trade in my Pixel for the better design, features, and general hardware prowess of Samsung. Plus, video-taking appears so much better on non-Pixel devices. Honestly, the Pixel's bare-bone camera experience is starting to age for me.
One UI is the other factor. I'm really impressed with what I've seen in its development and progress toward a cleaner and more sensible skin. Some of the little extra features are also appealing. Coupled with the timely security updates that have consistently been coming from Samsung, I'm optimistic the experience will be just as good overall.
We shall see in a couple of weeks! Fingers crossed.