What to learn - Ruby on Rails or ASP .NET MVC...given that am familiar with ASP .NET [closed]

I suggest you learn both!

I'm a professional ASP.Net developer by day, and a hobbyist RoR developer by night. Learning RoR will in fact make you a better .Net developer, and it's fun!

Also consider that one day you may in fact be able to write an ASP.NET MVC app in IronRuby instead of fussy old c# :)

There are many reasons I would recommend learning RoR over MVC

1. It's a much more mature stack. It's been around since 2005.
2. You get to learn a new programming language. "They" say you should learn a new programming language every year.
3. There is a very rich set of extensions to the base stack. Eg. HAML, Authentication gems, profiling and the list goes on and on.
4. You get to use database migrations out of the box. Something that is a bit of a breakthrough in database configuration management.
5. Dynamic languages give you a massive amount of flexibility.

That said: ASP.Net MVC is an awesome framework from Microsoft. I am not advocating dumping your stack and moving to the dark side. I just think it helps to have a broad understanding when it comes to technology.

If you're familiar with the Microsoft stack (Windows, IIS, SQL, ASP.NET) but not so familiar with the Linux stack (Apache, MySql, etc), then going with ASP.NET MVC over Ruby on Rails will cost you a lot less in the long run, in time spent on learning infrastructure.