Granted, I don't know much about Mint, but I do know that Ubuntu is by far the most user-friendly Linux distro I've used (among Red hat, Fedore, Suse..). Also, its online community dwarfs all others, which is a good thing when you need to ask something. Further still, most software is available for it in precompiled downloads. Not so with most other distros. Basically, Ubuntu is nowadays the "standard distro", most widely adapted, etc..