I think the bottom line is if they didn’t like Mint they’re not gonna like Ubuntu. Any criticism I can level at mint I can level even harder at Ubuntu. Before anyone can say anything for sure though it’d be important to know what they didn’t like about Mint and what it is that’s drawing them to Ubuntu.
As far as would I recommend Ubuntu? Honestly, no. I don’t recommend it to anyone. Its not easier to use than Mint if you want an easy to use Linux distro. Its basically no better than Windows if you’re issue with Windows was philosophical. From a technical standpoint I find it to be about the worst distro there is.
The list of distros I find myself recommending to people is as follows:
Mint (for noobs)
MX (for experienced users who don’t wanna Futz with stuff)
Antix (for constrained systems)
Arch (for experienced users who do wanna Futz with stuff)
Debian (for people who are on a futzing with stuff spectrum between MX and Arch, regardless of experience level)
Artix (for sickos who love the Futz, live for the futz, and found Arch to not be futzy enough)