ASP.NET all the way!
I've been using .NET and PHP for the last 6 years, and coding with visual studio is seriously a breeze!
Refactoring, intellisense, javascript debugging - with breakpoints!
I'm not really a fan of the postback mechanism, as this is dependant on javascript being enabled in the browser - uh oh!
But yeah, I learned C# and used my .NET experience to build console applications, windows services, bluetooth applications and windows forms too.
Forget Rails, Forget PHP. Get this.