If you're using Gmail, and you're considering alternatives for privacy reasons, then 100% without a doubt, objectively and unequivocably, Proton is the better choice of the two.

There are other email providers with privacy assurances, and yes, you can self-host, but don't let perfection be the enemy of the good.

To address the trustworthiness of Proton directly: I've been a Proton user for about 10 years. It gets the job done. I have complaints, but privacy is not among them.