2 year Proton user here, The only real issues I've encountered are the occasional short downtimes (they really aren't often). If you're ever worried about their status, they do have a status page here. I haven't ever had any trouble with people not receiving emails from me, and I don't travel as of right now. Anyways, I'd give their free plan a try and go from there, just to see what you think, but I think it's a fantastic option.

I feel the spam filter is as strong as Google. Receive a lot of spam, even though I didn't put my email on a random website, but the spam is not blocked.

Been using it for a bit over a year now. I've basically phased out all Google products, and I don't plan to go back. That said, I wish they would focus more on polishing the user experience than making new apps. The android and Linux experience are very poor right now, though they keep claiming they will get better soon.

Rock-solid and largely issue free for me for many years. I remember once having a site not accepting usernames from the “@protonmail.com” but the “@proton.me” worked w/o issue. Not bad for my most memorable issue in like 5 years.