Small company owner chiming in, needing to connect to an Exchange Server (2016) and Office 365 (transitioning to Business O365 sometime this year). Apple Mail is actually pretty nice to use with Exchange, and it's extensible. I use Outlook 2016 for Windows in a VM for 95% of my work-related email, and I also have an old Lumia 650 with a Win 10 ROM loaded as a supplementary email "notifier".
My company uses both Windows and Macs, but company email is restricted to the Windows clients for now. I'm demoing the Mac Outlook client, interested in it since MS announced (in January) that all of their Office applications moved to a unified code base for their key apps. I'm on the Fast Ring, and Outlook is improving mightily by the week - but I find that its configuration to be not as granular as the Office app. With Office 2019 in opt-in testing at the business/enterprise level (I haven't opted in), I'm holding out for that suite's email client before I bless the Mac client as being an option on my Macs and Mac VMs. Outlook for Windows for now, my judgment is reserved for a few more months...
Outlook on the Mac platform still restricts non-Exchange data to IMAP-only email accounts, but that's a non-issue for me.