I think the statistics say otherwise.
https://www.netmarketshare.com/oper...spx?qprid=10&qpcustomd=0&qpob=ColumnName+DESC - I've used those figures to calculate share figures for each platform separately.
Among other things, you'll see that El Capitan has the largest share of OS X, more than three times the share of Mavericks. Yosemite has double the share of Mavericks. That works out to 41% for El Capitan, 26% for Yosemite (67% combined), 13% for Mavericks, 6% for Mountain Lion, 7% for Lion, 4% for Snow Leopard, 0.5% for Leopard, and 0.2% for Tiger.
Meantime, over at Microsoft, Win 7 (54%) still has three times the share of Win 10 (17%), and Win 10 has less than 50% more share than XP, which was released in 2001 (17% to 12%)!
81% of Mac users are on the three most recent versions of the OS, while just 32% of Windows users are on the three most recent versions. Snow Leopard and Windows 7 were both released in 2009. Win 7 is in use on 54% of Windows machines, Snow Leopard is in use on 4% of Macs.
Personally, I never pay attention to user ratings of OSes - they're never better than middling, because so many people hate change. As with most Internet polling, people with negative opinions are far more likely to vote than those who are satisfied.
New-version adoption rates have gone through the roof since Apple moved to the free update model with Mavericks. I don't recall there being hordes of Mac users running out to buy the latest OS X DVDs. They had to
pay, after all! If I was to judge by postings here at MacRumors,
nobody paid to upgrade from Snow Leopard to Lion or from there to Mountain Lion (although the numbers say otherwise). It was all, "Don't upgrade, Snow Leopard is perfect!" (Well, you see that with every new OS release.) Among other things, free distribution was designed to bring all those "stragglers" along, and it seems to have worked pretty well. Large numbers upgraded directly from Snow Leopard to Mavericks.
It can be a mistake to project your particular preferences upon the rest of the public.
I'm sure you're quite aware that nearly every version of OS X is considered "the best" by a particular constituency. I find it particularly interesting that many of the negative comments in this thread have had to do with the appearance of the OS, rather than the technology. Some people care more for appearances than others - I'll take tech/features over appearance every day of the year.
I still don't understand what "flat" really means, but I'm not a graphic artist, so I'm not dialed into that particular lingo. Everywhere I look, I see drop shadows, translucence, and other features that add a greater sense of depth. The Apple icons on the dock aren't monolithic blocks of color, there are gradients everywhere.