Other vendors significantly mess around with the Android OS. Google's OS has better compatibility with stock android and will be patched more frequently than Samsung:
https://android.gadgethacks.com/news/pixel-3-xl-vs-galaxy-note-9-best-android-compared-0188411/Also, Samsung has been notoriously bad at pushing the Android monthly security patches, unlike the Pixel devices. Pixel 3 XL will get security patches for three years in addition to two letter updates (Android Q and Android R). While the Galaxy Note 9 should get a letter update, it will more than likely stop at Android P and stay behind in security patches, leaving it vulnerable to exploits that Google already patched.
Per privacy, many companies will attempt to sell your information, not just Google. Apple sells your information. There is no way to get around it. Further, most android phones already have Google's voice assistant, YouTube, and Google's apps installed. Buying a Samsung phone and installing Google Apps really means that you have to split your trust across multiple companies.
As far as other features besides camera, I have noticed the following:
- Suspected spam callers are marked in red when a call is received, with an easy block button
- Incoming phone calls can be sent to the google screening service, which translates the caller's message to text in real time, allowing one to answer and take the call
- You can tell Google to book a reservation at a restaurant at a certain time and the AI will call and book on your behalf
- The phone seems smart enough to tell when you are in a meeting, and will vibrate rather than ring, despite the ringer being on -- which has been useful