Neither.
S23+ would be my recommend if you want something similar in size to Pixel 8 Pro. If you can tolerate a bit larger and more square-cornered display, S23 Ultra.
S23+/Ultra mobile phones are faster in practical usage (other than snapping photos some of the time), have better battery resiliency, faster charging, offer more customization options, etc. than Pixel 8 Pro.
The only noteworthy downsides in my opinion:
- Camera and app integration is not quite the same as Pixel (especially in less than ideal situations)
- 7 years of software updates and security patches vs 5 years (including Android 17).
- OneUI Android updates and security patches are not released as quickly and staggered across different Samsung hardware platforms instead of "all (supported) Pixel phones" at once.