The most stable version of Windows EVER, in my experience, was NT 3.51 SP5 - and by MY standards I don't class that as "properly stable for a server" but closer than any other Windows version since.
 NT 4 SP 6 was fairly close.
 2000 never got as stable as NT 4 but was sorta in the same ballpark eventually.
 XP ... stable ..... don't make me LAUGH. NEVER was stable enough to run a server on for anything serious, and IMO was iffy for WORKSTATION usage from a reliability standpoint.

 The "server" versions seem to have improved some vs 2k, but haven't had AS MUCH experience with those - and I STILL have never seen anything in Windows on a server manage more than months of uptime, with the exception of ONE NT 3.51 SP5 server I saw manage almost 18 months of uptime before it flaked for the first time, and never more than a year after that.

 LINUX I have owned more than a few servers that went 15+ YEARS of "no downtime except for hardware failure, power outage longer than the UPS battery could last, or had to shut them down to move them" and more than a few that had 4+ YEARS of continuous uptime between moves/power outages of excessive length.
 One place I worked had a LINUX file server that had not been rebooted in almost 10 YEARS while I was working there (NCS had both a UPS setup AND a genset that interfaces with the UPS for longer outages when I was working there).

 On PRODUCTION controlling computers, Windows is a rarity IME - and ALWAYS had issues with low reliability where it WAS used as anything other than a "monitor what the dedicated hardware doing the ACTUAL WORK is doing" interface or as a "terminal to talk to the mainframe/server that's doing the ACTUAL work".

 Had one place replaced a QNX box with a Windows-based "upgrade system" from the same company - and after 2 months of nothing but problems and frequent downtime that was costing quite a bit of productivity, along with *3* visits from a FACTORY TECH to try to make it work right, the company put the QNX box BACK in place because it WORKED - despite being 10 year older hardware it worked FASTER AND MORE RELIABLY than the Windows-based machine that was supposed to be an UPGRADE.

 And yes, far too many "Enterprises" know that Windows is going to crash on them occasionally, and have work-arounds in place for when it does so - or they move their servers to a LINUX (or in some cases back in the day a UNIX) solution they can count on to just keep going and going and going and going....

 There's a reason the MAJORITY of web servers run on LINUX and have done so for a couple decades or so (BSD was the leader before that, in it's various flavors, after taking over from VMS).
 The only reason Windows is even in that competition is too many IT shops have lots of Windows experience but NO LINUX experience at all, and many other IT shops don't believe you CAN "mix and match" successfully.

 Hint - do you think Google runs on a Microsoft solution?
 Answer - no, they run their servers on their own customized LINUX version, and their standard in-house desktop OS is a modification of Ubuntu LINUX.

 This is not speculation, this is FACT from having worked with the stuff for decades as a tech and software tester.



 Have you ever been in one of the Azure server centers?
 I have - Quincy is quite close to where I live and I know a couple of the techs that work there.
 Azure as a platform is reliable - but only because it's designed for massive redundancy and fast fail-over when an individual server flakes out - and that's straight from techs that WORK with the infrastructure behind Azure.

 MOSIX based platforms can easily match the reliability of Azure.