"About Firefox updates:
Linux Mint uses the same Firefox package as Ubuntu from the same repository. Firefox is a level 2 update so every Mint user receives it by default." -Quote from a Mint Developer.
The two years I was using Linux Mint (now trying Manjaro), Firefox Updates were available at exactly the same time as on my other PC with Xubuntu on it (even if you let Mint Update Settings at default).
Every Distribution is different, has other advantages and disadvantages, so why not just test/read about them all and choose YOUR favorite... and be happy.
Those Distro-Wars are just stupid. But what really annoys me is when people start telling "facts" that are not true (see Firefox Updates), maybe those were not meant as a lie, but why then start talking about those things if one has no clue?