DXStudio was weak and convoluted last I tried it. It's not a patch on Unity or Blade3D. Blink3D looks weak too. For this type of tool, only Unity and Blade3D look worth a damn to me. Even they both have their weaknesses ( Mac-only dev, and some Windows compatibility issues with Unity, and XNA reliance with Blade3D ) but they are both very capable from what I've seen.
http://www.blade3d.com/ ( because I don't know if it's been linked to before on these forums. )
http://www.blade3d.com/ ( because I don't know if it's been linked to before on these forums. )