I'm considering learning a new language as an alternative to PHP. I'm considering Python and Ruby. Which one is a better language based on the following four criteria, and any other qualifiers you may have?

Which is more stable?
Which is more scaleable?
Which is more secure?
Which is easier to learn?

EDIT:
Keeping the original question intact, I'd like to add one more pair of questions.

Which is quicker to code with?
Which is quicker to learn? (Based on personal experience only please - to avoid holywars.)

EDIT2:
Sorry for not clarifying - mostly web development, some desktop programming would be a nice bonus.
pyfunc pretty much said it, but I'd like to offer two more thoughts:
1) Ruby will probably end up being a tiny bit more familiar as it a) can often optionally use a more C-like syntax, b) is not structured quite as foreignly as Python coming from PHP
2) They can both scale well, but Python will probably give you the most bang for your buck (CPU wise - and if you use Ruby, you're probably pretty well off using Ruby Enterprise and mod_rails, aka phusion passenger).
That's all - even considering those points, the difference may well be negligible, as the power of the language is all about how you use it, regardless of its inherent pros and cons.
Ruby or Python instead of PHP?