Generally speaking, the Python community believes the strength of Python is in its culture, which can be summed up by the Zen of Python: http://www.python.org/dev/peps/pep-0020/. Python also recieves much praise for being easy to learn, readability, productivity, expressiveness, and its library support, namely NumPy and SciPy (Python is often used in scientific computing for this very reason). Aside from this, Python programmers like it and that's reason enough. Performance for Python (and Ruby) is adequate for most use cases.
Personally, I don't like Python. If I want a dynamically typed language, I use Ruby, but I came to this conclusion after spending time with both languages, and it wasn't the feature set that sold me of one over the other, but rather how I felt while working in the language and its ecosystem. In other words, whether or not Python or Ruby are worth your time is a decision you'll only be able to make after using the language.
I believe in being language agnostic whenever possible. Don't hold strong opinions about languages. People invest a lot of time and energy into their tools. This is a "sunk cost." Their time and energy can't be reclaimed. So it's no surprise that, when asked, they will praise their tools -- even if they aren't objectively all that great -- solely to justify the costs. They aren't trying to convince you, they're trying to convince themselves. So don't waste time trying to find feature comparisons. All languages have redeemable values, and learning a new one is always a valuable exercise.
So give Python and Ruby a shot. You might find you actually like them, but not for the reasons you expected to. And if you don't like them, at least you'll know why.
I have to disagree with the last part of your post. Some languages are actually better in quantifiable ways; for example, shorter development time, better performance, etc.
But no language is best in every case. Putting skills into language agnostic pursuits means you can use whatever is objectively best as needed, ideally you'll have already used it.
Personally, I don't like Python. If I want a dynamically typed language, I use Ruby, but I came to this conclusion after spending time with both languages, and it wasn't the feature set that sold me of one over the other, but rather how I felt while working in the language and its ecosystem. In other words, whether or not Python or Ruby are worth your time is a decision you'll only be able to make after using the language.
I believe in being language agnostic whenever possible. Don't hold strong opinions about languages. People invest a lot of time and energy into their tools. This is a "sunk cost." Their time and energy can't be reclaimed. So it's no surprise that, when asked, they will praise their tools -- even if they aren't objectively all that great -- solely to justify the costs. They aren't trying to convince you, they're trying to convince themselves. So don't waste time trying to find feature comparisons. All languages have redeemable values, and learning a new one is always a valuable exercise.
So give Python and Ruby a shot. You might find you actually like them, but not for the reasons you expected to. And if you don't like them, at least you'll know why.