PK neglected to mention that:
3DS Max: $3495
Blender: $0
:)
From my other post: "in image and model work, you really do get what you pay for". Plus the trial of Max is free.
Add to which, some people find 3DSMax's interface truly abhorrent. I know a professional modeler who swears by Lightwave and regards Max as having a truly unusable interface.
It's what you are used to that matters more I think.
That's why I mentioned a good list of others, with the note that you're bound to like
one of them. I've known people who loved Maya and hated Max, despite their similarities, so the variety out there is definitely a good thing.
And on-topic, as symon said, you can do a lot with NifSkope to both build and repair meshes. You have to be careful to link nodes just how MW likes though, or the mesh can go funny.