What's your favorite open source CAS (computer algebra system)?
 

I would like to install a symbolic computing software (like Maxima or Axiom) on my computer and I would like to know which one you think is the best for mathematical and physics applications. The "best" means variety of functionalities (algebra, differential equations, plotting, integration), computing power (how many seconds it take to compute complicated integrals...), robustness (does it crashed frequently) etc.

Here's a list of some software: http://en.wikipedia.org/wiki/Compari...lgebra_systems

Thanks