Then create your Documents, Downloads etc. folders on it, and use symbolic links.
e.g. on MacOS, do something like this for each 'shared' folder:
rm -rf /home/rahim/Downloads
mkdir /Volumes/data/Downloads
ln -s /Volumes/data/Downloads /home/rahim
Imo it depends on what’s important to you but from purely a data recovery standpoint I’d say pick NTFS & use tuxera on the Mac & Linux has write support built in. This way you can have a 3rd partition w/ data shared btwn the 2 OS’s. Of course if your against that you can use hfs or ext4 & figure out how to mount those. NTFS will of course not work w/ the permission structure of either well.
One thing that I have also done is ensured that my actual Windows partition will never be mounted in write mode from any other OS by changing some settings. The VM partition is read-write obviously.
Windows for now is my primary OS but that may switch to Linux. In any event if the 200gb isn't enough space then I will likely just shuffle things around under Windows so that the VMs I am currently working with will be available to all 3. All in all I like this solution best, I dedicate the most space to my primary and I dedicate just enough to the rest while have the shared space as well. I feel confident this will not result in having to reload an entire OS, which is something I want to actively avoid and is a risk with dual or triple boot systems.