I gotta agree with the others that you should try various demos and take a look at their tools and workflow, since what is important is what suits the way you work and that it fullfills your needs. We've got both Max and Lightwave at work but personally I'm using Rhino on my PC and recently bought Universe 4 for my Mac. I am also considering Maya for it's character anmimation tools and flexibility (but still gotta save a lot of pennies up for that one even with the pricecut).

All apps have their strengths and weaknesses and once you've learned a 3D app it's often easy to forget how much work went into mastering it. The only thing that really matters is that you feel comfortable using it. In the end no tool will make you a better artist.