Scipy / Numpy is a defacto standard for scientific / numerical computing using python. The vast majority of packages are built on top of them (including Scitools). In many ways, it looks like Scitools is just a shell of connivance around Numpy / Scipy / Matplotlib.
Regarding support for Python 3, i.e. Numpy and Scipy, but Matplotlib is not there yet (although I think it can be supported in the development repository on github):
http://onpython3yet.com/packages/requirements?r=numpy%0D%0Amatplotlib%0D%0Ascipy
Personally, I have never used Scitools, since I prefer a lower level of control over using other libraries directly. I also stick with Python 2.7, since the full stack of scientific programming has not yet completed its migration to Python 3.
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