Which Pixel phone to use with GrapheneOS?

A quick rundown of all of the newer Google Pixel phone models 5 through 7 currently available as of 5 Sep 2023. I discuss:

Pixel 5
Pixel 6, 6 Pro and 6a
Pixel 7, 7 Pro and 7a

Overall best option for tight budget: Pixel 6
Overall best for mid range budget: Pixel 7
Overall best features: Pixel 6 Pro or 7 Pro