Many labs have done some sort of platform, so let's list some alternatives and think about why they do / don't meet our requirements. i.e. "What does SNAPPY do that nothing else does?"
IGSTK (Cleary et al. obsolete)
Slicer/SlicerIGT (lots of work with PLUS, Gabor Fichtinger et al)
All of the above are large C++ frameworks, which are difficult for researchers to extend. The exception might be Slicer/SlicerIGT which can be extended quickly via Python. The point of SNAPPY is to bring researchers who like MATLAB/Python closer to the application deployment via Python, and a minimal amount of C++ wrapped as Python.