I've been building web sites off an on for about 10 years. 2 years ago I started using ASP.Net. I'm working on 2 projects right now, one using ASP.Net MVC and the other using Java / JSF / Spring / Hibernate. 
I've also used other frameworks (cgi/perl, php, ASP, jsp, jsf). 

What do you think is the most productive programming environment for building web applications?

I have not used other frameworks such as Ruby on Rails, Glass Fish, etc. Are there any frameworks that I might be missing and should look at?

I'd really be interested in hearing opinions from someone with Ruby on Rails experience.