I haven't had registry issues since, I don't know Windows 95
That's great for your use case apparently. I develop/customize web applications and when the server is running on Linux or OS X, all the settings are neatly stored within the apps. With Windows settings could be in Registry and difficult to find, others are in the app, sometimes in both and people can't figure out why their setting is not working... the syntax can be weird and if you mess it up all hell breaks loose. I think you need Admin rights to work in Registry (which is another risky but standard way of working on Windows machines, everyone is Admin), but on unix everything can be neatly isolated.
OS X needs to be rebooted when it gets updated (unless I'm misunderstanding your point). Yes there are times I have to reboot windows for simple application installs which is baffling and a bit frustrating.
Far, far less and for a lot fewer reasons. With OS X, I often go several months without rebooting, only ever need to because of a major system software update. Some of the Linux servers I work with have been up literally for years and are running strong. If you don't update your Windows machines subsequently don't have to reboot frequently, eventually the systems creep to a crawl or start having memory faults in my experiences.
I've not seen any stability issues with the past few versions of Windows.
Probably depends on how often you reboot. At least due to frequent updates that require reboots, you probably reboot enough already. OS X and Linux can stay up for very long periods without needing reboots while remaining stable.
Can you define what you mean by Command line horrors, while its not a unix shell, the cmd shell is quite handy.
"while its not a unix shell" I hear you! With a unix shell you do not even need a remote desktop. It's night and day.
The install process is extremely simp, just click through a wizard, I'm not sure how laborious that is. I found install Office, and Adobe products to be the same level of laborious effort on Windows as OS X.
Apple's office apps are in the App Store and free. Just "install"! It works like the iOS or Android play store. You can install your (paid) apps on several machines. With Linux it's even way better than OS X or Windows except that OS X has a better consumer experience for purchasing software and sharing the same license across all your machines. With Linux (debian), let's say you need to step up LAMP, you just run a command like "sudo apt-get install lamp-server^" and it does everything for you handling all the dependencies and shared libraries efficiently.
By contrast, just try to install MSSQL and it might fail because you're missing the right version of .NET, then you have to go download that and come back and start over.