Re: Advantages to Windows 10
Over 8.1? The Metro crap is much easier to avoid. Other than that, I'll grant that it isn't at all obvious what's changed.
Over 7? The support for modern hardware is better. USB device support is noticeably less buggy, in my experience, though USB3 still needs work by somebody (either MS or the hardware vendors). Conversely, support for non-modern hardware might be patchy because of evil-or-incompetent driver vendors.
Over either? I don't personally believe that MS are serious about security patches on anything that they call a "legacy OS". Their almost-insane attempts to push 10 on everyone suggests active hostility to the idea of supporting these systems in future. 7 is out of mainstream support and 8.0 is already officially dead. (I suppose they might retro-fit the spyware at some point, if they haven't already done so...)
Over Linux Mint? It does a vastly better job than WINE of running crappy old Win32 software. You may not have any. Many domestic users don't or could find reasonable Linux alternatives. (I'm one such.) But if you do, good luck running it on WINE (https://appdb.winehq.org/), good luck trying to persuade the authors that they have any support obligations on that platform, and especially good luck if it is an in-house "app" and you aren't the manager of the software team that "developed" it.