I have just completed my transition from Catalina's Apple Mail to Outlook, on my desktop machine. It wasn't too difficult. The only reason I changed was the loss of a user-customizable column view. The largest effort was in copying my local ("On My Mac") mailboxes over to Outlook.
The first Apple computer I had on my desk at work was the Mac SE, and I've had Apple on my desk ever since. That's more than 30 years. So I suppose I can claim to be a loyal Apple user. But I found problems like having the Attachments column way off to the right -- where I can't see it at a glance and easily identify which messages have attachments and which don't -- to be too much to tolerate.
Aside from the column view issue, there are pros and cons to Outlook vs Apple Mail. But overall they are similar enough that I believe Outlook will be satisfactory. And I'm confident that MS won't degrade the product to any significant degree. I have no such confidence in Apple, especially if their goal is to bring MacOS, iOS, and iPadOS into greater conformity with each other, as some have speculated.
I do plan to continue with Apple Mail on my laptop, which is still running 10.14. But I don't use that machine to organize and manage my email, just to view it. So I can probably tolerate a crippled column view if and when I upgrade it to 10.15.