When comparing Windows vs Plan 9, the Slant community recommends Windows for most people. In the question“What is the best operating system for a developer?” Windows is ranked 5th while Plan 9 is ranked 8th.
Ranked in these QuestionsQuestion Ranking
Pro The most solid choice for .NET development
Pro Widely used
Windows is the most-used desktop OS in the world.
Pro Windows comes first
Windows is the most used platform in the world. If you build something and need a third-party software it will most likely run on Windows. Not because it's good, but because everyone uses it.
Pro Best driver support of any OS
No other OS comes close to supporting as much hardware as Windows 10 does. Because it's the most popular OS, the bulk of hardware manufacturers support Windows first, and all other operating systems second.
Pro Free access to great development IDE in Visual Studio Community
Pro Ubuntu bash shell
Windows has a binary compatible Ubuntu shell to run non-Windows apps natively.
Pro Touch screen support
You still can't get touch support on a Mac... Windows has had touch for 5+ years now.
Pro Best support for Visual Basic
Pro Free with most new computers
At least the non-Apple variety at any rate.
Pro Designed to allow for multiple computers to work as if they were one
With Plan 9, computers are turned into terminals where you can access files and processing units which can be located elsewhere. Data storage is handled by another external server. This means that instead of each person having their own individual computer with all the required parts, all of the computing and storage is done in a central area and everything is networked in together.
Con Weak default terminal
The standard terminal lacks basic features that Linux and OSX has. Alternatives to the default terminal for Window can be found here.
Con Most software is closed source, including the operating system itself
Con Uses more resources than most alternatives
Con Lacks package management
It is not easy to install/keep current development packages that developers need and use.
Con Limited in its flexibility
Window managers, startup systems, and system components cannot be changed.
Con Scanning for viruses makes builds slow
Compiling a project means reading and writing a lot of files. Even fast anti-virus software slows down the build time (which is almost always too long).
Con Maintenance is time-consuming
Previous versions needed to be formatted ever 6 months to maintain performance.
Con There are some privacy issues
By definition, it's spyware. Pre-compromised OS.
Con Embarrassing to give talks
On conferences or in user groups the audience laugh at speakers presenting their talk on a Windows machine.
Con Difficult to use software made for other systems
Plan 9 is very different from most other operating systems, and as such it's extremely difficult to bring in software designed for other operating systems ('porting').
Con No fully featured web browser
As indicated on the official Bell Labs webpage, there is no full featured web browser currently working on Plan 9.