I think much of that "Tor on Windows 10 is no good" is hyperbole.
It's true that Windows 10 sends an awful lot of data home to Redmond. But this is completely independent of Tor. If you use the Tor Browser to browse the net, I don't see how Windows 10's tendency to phone home would negatively affect your anonymity in Tor, since it will phone home in the clear, while your browsing will happen over the Tor network, so the two data streams have nothing to do with each other.
There are risks, most notably the following:
The large number of installed Windows platforms makes Windows an interesting target for attacks. So zero-day attacks which target the mozilla browser variants on windows will often work against the Tor browser bundle, too. Once the Tor Browser is compromised, you really are in trouble because it then becomes possible to deanonymize you. I think the FBI did exactly that a few years ago to identify visitors of illegal services provided through the Tor network.
There's another problem if your computer is stolen. It might be possible, maybe even easy, to find out what you've been browsing in the Tor Browser due to Windows's less than ideal handling of user privacy while you're working with your computer. For example, parts of your browsing history may find their way onto permanent storage, maybe via the paging system or as deleted files etc. Its harder to counter this in windows than in, say, Linux or even a live distribution such as Tails.
But basically, if you're not trying to stay hidden from organizations with very large budgets, I'd say Tor on Windows works just as advertised. And if you do want to stay hidden from said organizations, you should think much deeper about opsec than just use Tor.