I am not a privacy expert. I have found the following to be useful sources of information about privacy and am sharing them to help other people:
That One Privacy Site: The site has excellent VPN reviews. The site also has valuable information about email providers.
Privacy Tools: Provides knowledge and tools to protect your privacy against mass surveillance.
Techlore YouTube Channel: Useful privacy-related tutorials in plain English.
The Complete Privacy and Security Podcast is a weekly podcast that helps listeners to maintain their privacy in the digital age.
Berkman Klein Center for Internet & Society at Harvard University: The Center brings “together the sharpest, most thoughtful people from around the globe to tackle the biggest challenges presented by the Internet.”
ProtonMail: Encrypted Email and VPN provider in Switzerland
Tutanota: Encrypted Email provider in Germany
Tutanota Guide to Leaving Google
Secure Messaging Apps Comparison
Choosing a Linux Distribution
But see also:
If your main worry is that hackers could gain access to your email, then you should rely on Gmail. To be clear, for a majority of users, the threat of hackers trying to break into their emails looking for a way to make a quick buck is more real than the threat of a government investigating them as part of a crime. With the proliferation of phishing attempts and the threat of hackers obtaining your password via hacks of other services, this is what the average consumer should be worried about.
Google has one of the best teams of security engineers in the world. Moreover, the company has several strong security mechanisms for users to protect their account. Vice: Gmail vs ProtonMail: Which is More Secure?
I have never heard of a successful hack of Gmail.