If say I want to build a web application and new to Ruby, Python and Perl. But I want to use one of the RoR, Flask (or Django), Mojolicious. Which one should I go for. I.e. either one it had some advantage than other ? Rather, I know Python so I should go for Flask, argument.
In the Perl realm I chose Mojolicious because it has very little dependencies. It does not come with an ORM or a built in user login. If you wanted that, Catalyst is a better way to go. The Mojo Lite aspect of Mojolicious makes it really easy to get a prototype up and running.
I feel that it's more important to learn the fundamentals of the base language than it is to focus on any one particular framework. Virtually any web application of any measurable complexity is going to lead you into writing code outside the DSL that a framework might encumber you with.