As you can tell it’s something of an obsession for me
Regarding Slicer, yes, the Python interface is extremely powerful and flexible. For some of us it has become our main tool for taking on the complexities of real-world medical imaging research because so many tricky issues are already addressed. You have SimpleITK, VTK, numpy, Qt, and so many other useful things right at your fingertips on all major computing platforms.
Of course before anyone else points it out, Slicer is a big beast with a learning curve so it’s not the only way to go.
Here are some links to help you out, and you are always welcome over at discourse.slicer.org.