There's the up-and-comer,
LLVM. Apple has made it the default compiler in XCode 4. You can build it with Microsoft's
Visual Studio. The
ClangVSx add-in lets you use LLVM from within Visual Studio.
The core of LLVM is a compiler backend, responsible for code generation but little else. You can use the
clang frontend for parsing, or a GCC compatible frontend, or another frontend of someone else's devising (which means LLVM can compile from potentially any source language by switching the frontend).
At the start of this year, Cristophe Riccio published a
performance comparison of Visual C++, LLVM and GCC.