I almost always choose the Microsoft stack over anything else because of Visual Studio, the available tools and how easily I can get started programming with a particular new framework.
Please, that was only an example; it may be other stacks for other people.
I am not building real time, mission critical apps where a nuclear power plant would explode if my app didn't perform well... More like small business apps.
But when I tell this to other programmers, even before they react, I feel I might have embarrassed myself - choosing a stack because of the IDE?!.. ease of setup?! I feel the "pros" choose the stack by other "important" things I am not aware of and in the grand scheme of things, IDE and ease of setting up dev env don't matter much. I feel it is a little immature to do what I am doing.
Is it really a bad thing?
Note that I also choose the Microsoft stack because of a lot of other reasons (C# is an amazing language and .Net is an awesome platform).. but IDE, tools and dev env setup play a big part for me.
Also note that I am a 1 man dev shop, very occasionally 2 or max 3.