Moving to Mac after 20 years using Windows

First, welcome to the Mac world. As a user of Macs since they were introduced, I hope you'll enjoy it here, and that you'll find the transition not to be too traumatic.

In terms of Quicken, it's definitely worth being aware that Quicken Mac and Quicken Windows are close cousins, not identical twins. There are some things which Quicken Mac actually does better than Quicken Windows, but there are a number of features, large and small, which do not yet exist in Quicken Mac. (More get added roughly every other month, but it will take years to add all the features from Quicken Windows, and some may never be added.)

You can study the Quicken product comparison chart to look for which features are marked Windows-only. You can also dive into many threads on this forum regarding Windows to Mac conversions. But unless there's something very specific you want to know about in advance, the best way to see what's different between the products is to take Quicken Mac for a drive. 

Because we all use Quicken differently, and utilize different features, the differences may be inconsequential to you or may pose significant problems. Many thousands of former Quicken Windows users have migrated to Quicken Mac and are either very happy with it or at least tolerate it, but some find a key feature missing and decide to continue using Quicken Windows. You say you want to insure basic functionality, and I think you'll definitely find that — although how you and I define "basic" may or may not align.

I would therefore suggest a different approach than @Gilles9 did above. Using Quicken Windows in a Virtual Machine on a Mac is definitely an option if you determine you are unable to make the transition the native Quicken Mac. But I would suggest first trying the native Quicken Mac to see if your data transfers successfully and if it can meet your needs.

If you still have your Windows machine, the optimal thing would be to continue to use Quicken on the Windows machine for a short time while using Quicken Mac in parallel. There's a bit of a learning curve to the differences in the user interface, so you need to allow a little time to get over the knee-jerk "it's different!" reaction almost everyone has and try to settle into using it day to day. Hopefully, you will find Quicken Mac provides at least the basic functionality you need, and that there are no "show-stopper" missing features. Just be sure to give Quicken Mac a fair trial, which for many people means using it for at least a few weeks.

If in the end you conclude it is missing something so crucial that it will not meet your needs, you can then move to the Quicken Windows in a VM option as a fall-back. (You'll likely need to buy a Windows license, and probably to buy a license for the VM software, so there's one time and ongoing expense involved… and who wants to maintain and patch and update two operating systems if you can get by with only one!)