I've recommended this before, and I'm not ashamed to do it again.
For C/C++ dev, I'm using
AmiDevCpp and WinUAE. AmiDevCpp is a C/C++ dev tool for Windows, which builds Amiga executables.
But, for demoscene stuff there's nothing like assebly coding on the real thing. AsmOne is my personal favorite, stuck with it since the good old days. :-)
