Win10 home
remote desktop solution.
Also I would not say that Win10 is unstable. It has a mind of its own and needs configuring so it does not do stupid things like doing an update in the middle of the night during an imaging run. This particular problem can be easily solved by setting the network connection as metered, on Win10 home or pro.
Also there are compatibility issues with Win10 and ASI120 USB2.0 cameras and those cameras cannot be used for guiding. But only on some machines...
Regarding reverting to Win7, people have old Win7 copies or get Win7 from not so legitimate sources. Also newer machines may not have drivers for Win7, for example my laptop has drivers only for Win10 so going back to 7 is not an option.
And to your original question, as previously said get 8GB of RAM, SSD and not the lowest end CPU. The rest won't make much difference.