The MS stack is better than a lot of people give it credit for. Back in the old days of ASP.NET webforms I'd agree that it sucked, but things have changed a lot since then.

There's a web framework similar to RoR. C# is fast out of the box, strongly typed, and easy to work with. Also it's similar to JS so working with the two simultaneously isn't jarring. Visual Studio is arguably the best in class IDE. IIS is fast and can do everything you'd expect. Most tools have a GUI default, which really helped when I was learning.

Windows licensing costs are minimal compared to the total cost of a server (like an extra $20/month). I ran a db-driven site with 1,000-2,000 concurrent users, 30-50 reqs/s, and 40mil pageviews/month with a single $100/month Rackspace VM. SQL Server can get expensive when you start scaling up, but it's easy to switch over to Postgres when that happens.

Also I kinda like how steady it is. I got into development to build products, not to be constantly on the edge learning about the latest libraries or paradigm shifts. That's what frontend JS is for.