Definitely disgruntled by the way Google Apps went from being free for the last decade of my life to costing ~$120/mo for myself and my family. I don't think I can leave Google at this point, but if I was strapped for cash I would choose a different platform. Otherwise, I would still go with Google just due to their dominance in this space and integration with other companies. Calendar invites, meet etc being the primary thing
My current company is using Proton for mail/calendar but we still need Google accounts in order to access things like Google Cloud. We have Google Calendar but not Email. So there is this frustrating bifurcation between mail and some calendar on Proton and then some Calendar items on Google. I wish that Calendar sharing/sync was a more solved problem these days because keeping them syncronized is a nightmare.
Anyway glad to hear from the thread here that Zoho is a worthy competitor and might consider it in the future. They have been around for a very long time.