Which browser is easiest to develop a browser extension for?
I am interested in learning to develop browser extensions for most major browsers (Chrome, Firefox, Safari, Opera, IE), but I am unsure of where to start. To keep my interest up, I would like to start developing for the browser which has the gentlest learning curve.

So, what is your experience developing extensions for different browsers? Naturally, one must have developed for more than one browser in order to give a reasonable answer.

I am an experienced web developer, and also have no problems with C++/Java/Ruby/Erlang, etc, so the question is not what I am capable of learning, but rather what I most quickly would reap the fruits of.
Which browser is easiest to develop a browser extension for?
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I am interested in learning to develop browser extensions for most major browsers (Chrome, Firefox, Safari, Opera, IE), but I am unsure of where to start. To keep my interest up, I would like to start developing for the browser which has the gentlest learning curve.

So, what is your experience developing extensions for different browsers? Naturally, one must have developed for more than one browser in order to give a reasonable answer.

I am an experienced web developer, and also have no problems with C++/Java/Ruby/Erlang, etc, so the question is not what I am capable of learning, but rather what I most quickly would reap the fruits of.