macos as vm guest

[macports at parvis.nl]

after my development mac mini died (and the time backup appeared to be corrupt) i had to buy another mac. 
now i have a 2013 imac that can run catalina, but sometimes i also need 10.11 for older hardware and software, and 10.13 for compatibilty with our other macs.

i would like these 10.11 and 10.13 as vm guest under 10.15.

which hypervisor should i use (paralells desktop, vmware, virtualbox, other)?



currently i'm trying parallels desktop 15 on 10.13 with 10.11 guest.

did a basic install and now on the vm guest in recovery mode run rsync from the original partition to the guest disk.

is there a better way? parallels has a transporter for windows but not for mac. is there a hidden conversion utility?