Hi all -
I've got to a basic/intermediate level of skill with PHP, Zend and vanilla JS/jQuery and I'm looking to invest some time in learning some new technologies (for career purposes and also for a bit of fun). Here's my shortlist

Sproutcore/Capuccino platform: because they makes cool client side web apps - plus Capuccino uses Objective C which would help working towards some iPhone dev.

MooTools: I like the traditional OOP syntax it imparts - and I want to learn something a bit more "heavy weight" than jQuery. Maybe even Dojo or YUI.

Ruby/Python: had a little tinker with both - but found that hosting is hard to come by and not sure how relevant Ruby is at the moment, or how applicable Python is to the kind of work we get in the office.

So basically I'm looking for some opinions on which of these is most worthy of the investment. Currently I really like the idea of spending some more time on client-side, having focussed on grokking OOP/Zend for a while now.