I'm a reasonably privacy conscious individual, and I trust my own personal data to Workspace because having worked on Workspace for two years at Google, I saw how carefully Workspace user data was treated, especially for paid users.
None of that is to address the other points you bring up - simpler, cheaper - but I wanted to emphasize that I actually would trust Google more in this area than a random third-party hosted email solution. Someone like a protonmail or fastmail I don't consider "random", and I assume MSFT is as careful as Google given their enterprise background - but from smaller companies, I have a hard time believing they've invested so much effort in protecting user data as Google has.
(obligatory disclosure: I work for Google, used to work on Workspace until about 6 months ago, just my opinions)
I used to use Zoho which was fine, but at $6/mo was only offering 10GB per user (rather than 200/5 = 40GB) and didn't handle things like photo storage.
I looked at Microsoft 365 (formerly Office 365) which seems like a good deal at $8.33/mo ($99.99/year). Each user gets 1TB of storage, it comes with Microsoft Office (both web and the programs), OneDrive, email, Microsoft Editor (for things like grammar checking), etc. Ultimately, I didn't want to transfer our domains to GoDaddy and that's the only way Microsoft supports custom domains for email. Still, if you have a family of 5, that $8.33 becomes $1.67/mo which is really cheap considering that it comes with a full version of Microsoft Office and 1TB of storage per-user (with Dropbox-like OneDrive). Google charges $6/user for 30GB and $12/user for 2TB. While 2TB is more than the 1TB offered by Microsoft, $12 is a lot more than $1.67 (and you don't get Microsoft Office).
iCloud+ doesn't come with as much stuff as Microsoft 365, but it's been nice having something that feels like a simple email experience. No more fancy auto-classification of my email. I can just set up some simple rules (though they execute on the client and not the server) and I'm enjoying using Apple's Mail app. At $0.60/user, iCloud+ is working nicely. But I can definitely see why someone would like Microsoft 365. Their family plan is an amazing value.
I moved email to MXRoute and spent some painful time migrating to standard Google accounts-- imapsync to copy some email over to the new account, hacking Partner Share to get photos moved over, resetting all the Home devices.
It worked great with a couple caveats. All my store purchases and $75 of credit are on the old account and they cannot be migrated. This means I keep my GSuite account as a secondary account on the phone, not a huge deal. I lost location history and other such unmigratable metadata.
I use K9 Mail and Thunderbird and am generally pleased with them. After a week of tweaking I see better spam handling than Gmail, which was a surprise.
Overall very glad I got it done.
Importantly this just works which is more than I can say for anything else I've tried ... anecdotes below...
I was using Fastmail before which is a good cross platform solution but the whole solution goes down the toilet if you want to use their official apps and offline support. Third party mail clients are almost universally complete garbage due to disparity over IMAP mailbox naming, sync issues and corruption. I haven't found one that works properly.
I fell out with Google and GSuite before this because something fucked up my domain provisioning and they couldn't fix it via support. Also I found out rather rapidly that the moment I converted my account to a paid GSuite account that my YouTube account required a $30 payment to be made before I could post videos to my own channel suddenly. They held my YT account to ransom and couldn't fix a provisioning issue. No chance. I will never deal with them again.
On Office 365 I deal with this at work every day and it's horrible. It started off reasonable but the feature load is weighing the whole solution down and now it's a crapfest of pain. Even the authentication processes are utterly painful every day requiring a half arsed authenticator app that works 50% of the time. I still maintain an office 365 family account so the kids can use the desktop apps for school work.
As for privacy, I think it is well oversold in the email space. The communication protocols don't guarantee privacy and no legal jurisdiction is particularly friendly. I think it's better to focus on deliverability and using another technology for secure or private communications. I myself use email only as the usual e-commerce and event receipt handling system. Out of the 100 or so people I have in my contacts, only my mother still actually communicates via email.
Alternatively, if your family is on the Apple ecosystem, iCloud custom domain email works great, the only issue being that you get a limited number of email addresses per user and it doesn't support wildcard addressing.
I think that fastmail's implementation of custom domains and wildcard alias sending is the best I've seen to date.
That might not be a feature you care about, but I'd certainly consider Fastmail either way. Their domain DNS checklist page is really helpful and responsive in helping check you've set it all up correctly (DKIM, SPF etc).
(I know that’s not ideal for some use cases, but is workable for us so figured I’d share.)
I've wondered about alternatives, so interested to see what shows up in this thread.
There is also Yunohost along similar lines.
I still don’t have an answer for a Google docs replacement. The combination of sharing, mobile support, and not being stupid expensive is surprisingly hard to find.
Office365 has terrible file-syncing across devices, most other alternatives lack in the office-app department.
Here's the process I'm using, for anyone who might be considering it.
Fastmail can copy all your past Gmail to your new Fastmail account. I didn't do that because I'm planning on keeping the Gmail account, so can get to past email anytime I need it, and it's mostly old junk I'll never need again (I'm only using about 3GB out of 30GB for a free account). Also, if you have labeled email, each label on an email causes it to be duplicated at Fastmail.
Fastmail can be setup to fetch your Gmail with IMAP every 5 minutes or POP your email periodically, with or without deleting it from Gmail. I tried that, but it appeared what actually happened is that it fetched Gmail only when I clicked on the Inbox. Which is fine, but I liked how Fastmail changes the browser tabs to show when email is received, and that didn't work right (I waited 20 minutes and it never indicated there was new email.)
So instead, I set Gmail to forward mail to Fastmail. Because I had both business (HashBackup) and personal email going to the same Gmail account, and wanted to separate the two at Fastmail, I had to use some tricks. Gmail normally only forwards email to one email address, and I wanted each Gmail to be forwarded to 2 Fastmail addresses. To do this, you have to use the regular forwarding mechanism for each Fastmail address separately, to authorize your 2 Fastmail email addresses, then disable it altogether and use 2 forwarding filters at Gmail. On Fastmail, I just delete the redundant email. It's a lot easier than routing Gmail to 1 Fastmail address and then forwarding it to the other Fastmail address, and each email looks like the original at Fastmail rather than 1 looking like a forwarded email.
With Gmail, I was letting messages age and accumulate in the Inbox. To make it easier to see new Gmail that might be a straggler service I need to update, I enabled the Javascript Gmail interface, selected all Inbox messages (18K!) and moved them to the Archive folder. (Then promptly disabled the Gmail Javascript interface because all those icons make it impossible to use!) So old email is still available for searching if I need it, but it isn't cluttering up my Gmail Inbox. On Fastmail, I'm trying out keeping my Inbox clear and trashing emails after I respond. I have it setup to automatically delete Trash emails older than a year (you can leave them forever if you prefer).
To let people know about the switch, I added a Gmail vacation message that says "I got your email, I'm changing email addresses, for personal use blah, for business, use blah". That causes a bounce once in a while, but Fastmail puts those in the Spam folder.
Then, as I have time, I've been signing in and changing email address on various services I use. There are about 40 of these.
With a custom domain account ($45/year for 2 years) Fastmail also has options like hosting a static website and using your storage as file storage with FTP or browser uploading & downloading. I'm not using that, but coming from Workspace, it might be something you need. I just tried it out, and it's nice! I uploaded a file to my file space, it defaults to private, and you can create a special link to share the file with others. I tried doing this with Apple iCloud last night for some server photos and couldn't make heads or tails out of it, but with Fastmail today it was easy. Fastmail will also host your domain name, so you don't need to mess with a VM somewhere. I'm using Linode to host my domain because I need a VM for other HashBackup-related stuff.
Fastmail has Notes and a Calendar too, but I haven't used those. I also haven't downloaded the Fastmail phone app, but if it's anything like the website, I'm sure it's nice too.