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.
To get a quick feel for each and see which one "tastes" better I would suggest taking each one for a spin on a selection of problems on ProjectEeuler. PE is more about algorithms and math but some of thee simpler problems are a great way to get going with syntax and some core library features such as file IO etc.
Ruby or Python instead of PHP?