Using older versions of Outlook for Mac for personal email and calendar
For me/us, using Outlook is a deliberate choice, that allows our team to work with all functionality across platforms. Apple Mail and most other mail apps simply do not provide the tools and options the current/legacy Outlook has. The New Outlook for Mac seems to be on a direction of being as useless or limited as many of the non-business mail apps that we have tested as possible alternatives.
We are generally very happy with Microsoft Office, and we heavily rely on it across Windows, macOS, and iOS. The integration of mail, calendar, tasks and contacts in one interface, with the possibility to use various mail servers and protocols, while having online and offline access (local folders!) to data stores is what makes Outlook a business productivity tool. The dumbing down and oversimplification of the interface are not helping, at all.
Outlook is supposed to be the main communication hub that connects to various resources, incl. on-premises and online Exchange instances, Teams (Groups), shared calendars, local folders (with subfolders!), app add-ins (eg. Hubspot/Nimble/Slack), corporate as well as private mail accounts (Google, Apple, IMAP, etc.).
The current/updated version still doesn't offer all of this, and this is even known and listed as open issues. Pushing the New Outlook for Mac only emphasizes on it not being ready. This is my main frustration: we do not want to abandon Outlook, we simply ask to prevent the unfinished product from being shoved down our throats as long as it isn't ready.
Apple doesn't have an integrated alternative. And doesn't offer an office suite for Windows users.