For Virtual Machines I create, as well as on old computers I use, I'd like to turn off gdm/lightdm in order to get better performance. I don't like to boot into single user mode ("linux single") because using root is a bad practice, and I also prefer to keep an easy way to boot back into graphic mode, so when graphic mode is required, no extra commands would be needed.
The way I see as the most useful is to configure Grub to show a menu item for "Ubuntu Text mode" in addition to the regular boot and the recovery mode, and set the text mode as default. I tried to do it myself, but Grub2 configuration files on
/etc/grub.d/ looks too cryptic to me, and
/etc/defaults/grub can set booting into text but it doesn't seems to allow keeping a menu item for graphical booting as well as setting text or graphics as default, and I prefer to keep the booting process simple to novice users so they won't need to mess with starting services manually or editing the kernel boot command line in Grub2.