I'm planning to purchase Maya soon. For me the big reason is animation. Modeling tools are all pretty much the same no matter what package you use but I find the animation tools in Maya much faster to use than 3D Studio Max or Lightwave (like you, I've never used SoftImage.) In particular tools like Paint Weights make it really easy to rig characters in Maya, the hypergraph makes selecting stuff trivial (until I used it I never really thought about how much of a chore selecting stuff is in most tools,) and tools like the graph editor and dope sheet make it really easy to tweak animation by moving keys around and adjust interpolation. Note that you can download a free trial of Maya (PLE, the Personal Learning Edition) from aliaswavefront.com
The lack of a b3d exporter is concerning but then 3D Studio Max doesn't have one either and the current conversion paths (eg. export to DirectX, convert to b3d using Ultimate Unwrap) works just as well with Maya.
The lack of a b3d exporter is concerning but then 3D Studio Max doesn't have one either and the current conversion paths (eg. export to DirectX, convert to b3d using Ultimate Unwrap) works just as well with Maya.