Hi, I have used Mimics. You don't need to train or anything, very easy to get up and running on it. It's very good at extracting 3D info from stacks, a DICOM viewer with the ability to interpolate your 2d info to 3D. If you've used ITK-snap it's similar but better (less buggy and more powerful). I don't know how much it costs but have heard mimics is expensive. They work deals with educational licensing and also have offered short term licenses to some people I've worked with. ITK Snap is free though!