I feel the same way as you but not because I think one is less evil. Rather, it's because Google brings me much more value in its search engine and productivity suite.
It seems like there are a lot more political activists working at Google. It also seems likely that this will backfire in a spectacular way at some point.
The risk here is politically strategic data leaks of individual user data - not Cambridge Analytica-like situations. Could be blackmail material on a few key people, or perhaps a giant data leak on millions of people from the "enemy side".
The point is that sharing data with Google is just as dangerous.
"Political activists" is just one (rather unlikely) insider threat among many that a company like Google has to mitigate.
It is technically impossible for something like Protonmail to read my emails.
This feature does not exist with most other email providers e.g. Gmail.
Even if we drop the activist threat model there is still the possibility of external hacking.
Possibly organized crime. I heard of one Yandex employee caught selling access to Yandex users email accounts.
Maybe something similar could happen?
I do not know which internal systems Google or related companies have to prevent employees from accessing user data.
Does anyone here have resources on this topic?
After all, not skydiving is also dangerous.
If I have to choose only between Facebook and Google, I'd choose Google to have my data.