I would like to de-google myself. I've already changed search engines, which is easy enough, but I'm having difficulty finding a viable alternative to Gmail. I've been using Protonmail but to be honest it's very basic and doesn't work that well. Any suggestions?
Protonmail was what I was going to suggest... lol. Why don't you like it? I don't feel it is very basic.
Maybe it's just me but I have had problems with the search facility and emails disappearing. Because of that I don't feel very confident about relying on it for important information.
You can use Outlook.com or iCloud.com --- Check this out --> https://clean.email/alternatives-to-gmail <--
If you're looking for something longterm imo try to find something that is fido 2fa compatible. Fido is the gold standard for security, it is a physical key you use.