I simply don't get the point why choosing zfs within a VM, except you're a zfs-expert and your main purpose of this installation would be to particulary examine special zfs issues.
Chose ufs.
I daresay: Second best fs there is. ?
The handling of the system is the same.
If one wants to get into FreeBSD (praiseworthy! ?), especially if one just wants to take a peek, zfs changes nothing about the usage, look and feel of the system, but adds complexity, hooks and strings, only.
If you just use the default from the installer, you will not recognize any difference, except complications: "...??? what should I choose..." - see?! ?
Btw.:
Those diskpartition tools, such as gparted live, clonezille, etc., are extremley useful, saved my arse dozens of times ? - on other systems.
At least the versions I know (>3..4y) also cannot freebsd-ufs.
But with FreeBSD you don't need them.
Either you're on a VM, then your disk is imaginary, a file on your host's fs, and you can simply use the tools given by that OS.
Or you're running FreeBSD natively. Then you don't need them neither, because FreeBSD provides tools, at least as powerful to do at least the same jobs (also partitions containing other fs. [But, OK, those are not by default all with GUI part of FreeBSD's standard installation. But most you'll find in the HB, or here in this forum.]
