Tired of ASP.NET, which of the following should I learn and why?
Let's start by clarifying your question. Why are you "tired of ASP.NET?" Is it because of the tedious webforms model that tries so hard to protect you from the browser/server conversation that it ends up getting in the way?
Or is it because you have been trying to work with one of the tiresome 3rd party enhancement controls that build on the tedium of the webforms model?
Or do are you simply tired of working with five different languages at once: ASP.NET, HTML, CSS, Javascript, and C#/VB?
If you answered yes to the first two of these questions here's some advice:

Get some rest.
Try ASP.NET MVC. It gets out of your way and lets you work with the browser and IIS
Realize that changing web development models will be difficult no matter which one you choose to move to. The path is smoother the fewer things you change (see number 2).

If you answered yes only to the 3rd question (five different languages) then all I can tell you is, welcome to web development. It will be this way for awhile.
Which of the following technology is easy to learn and fun for developing a website? If you could only pick one which would it be and why

Clojure/Compojure+Ring/Moustache+Ring
Groovy/Grails 
Python/Django 
Ruby/Rails
Turbogear
Cappuccino or Sproutcore
Javascript/jQuery