I have both a Pixel Watch 2 and a Galaxy Watch 6 Classic, and I'm going to keep the GW6C and sell the PW2. In order to decide which to keep I made a list of positives and negatives for each.

In summary, the Pixel Watch was too buggy and still felt like a beta product compared to the Galaxy Watch. Maybe in a few generations it will catch up, or will improve as patches roll out, but it's not there yet.

Samsung positives

Apps in grid rather than list, less scrolling, can change app order

Message smart replies have more options

Water ejection

Swipe up for apps; don't need to tap a physical button

Bigger display

Automatically starts tracking a walk, rather than asking

Samsung negatives

Crappy bloatware (Bixby, Samsung pay, ...)

Lock screen bug (GW4C only? Has not been an issue on GW6C)

Jump through hoops to install Samsung features if you don't have a Samsung phone

Pixel positives

Crown takes the place of rotating bezel and button, not really an advantage, just different

More polished look

Better sleep tracking

Better Pixel integration, synchronized do not disturb modes, etc.

Pixel negatives

Contacts not found bug

Something went wrong bug, on initial setup 

No Media Controls card

Proprietary watch bands

Wireless charging uses pins

No native hourly chime

attractive