[prmoustache]

What do you mean by "unconfigurable".

Gnome boxes on my distro has an "Edit Configuration" button that allows yu to modify the libvirt xml config.

I'd say it is more user friendly than virt-manager if you want to deploy quickly a vm to run a live environment. Also the ability to pause the vm automatically when not accessing it is nice when you just want a separate vm to access, say, your ebanking or want to run quick tests.

It is less user friendly than virt-manager if you want to do a lot of customization but it is still configurable as you get access to the vm xml file. So if you have a cheatsheet or a text file containing usual additionnal configuration you need it is just a copy/paste away.

I have virt-manager installed on my laptop but I still use gnome boxes when I want a vm for quick tests or specific dev environments, when I want to try out a beta version of a distro before committing to upgrade mine, or if I need to run some quick tests on a specific distro that I use somewhere else in a more critical environment.