The only commercial alternative I know of is Qt Creator, and that is still in beta. I don't know it so I can't consider it for the comparison.
Apart from that, the choice is obvious: if you want to do portable C++ or C++/CLI, take Visual Studio 2008; the debugger is amazing, and the compiler is highly standards-compliant. But for rich-client Windows applications, Windows database apps, COM servers and clients or Delphi interop, take C++Builder. There's nothing as productive as VCL when it comes to rich client UI.