I've not used VCC, GCC or Storm for comparison, though I like SAS/C due to its ease of use and good documentation. Never had any problems with it though I didn't like the source editor it comes with due to the non-standard keyboard commands for copy, paste, etc.
I develop in C, assembly, ARexx, AmigaGuide and HTML;
CubicIDE works nicely with all of these in terms of syntax highlighting and quick access to tools specific to the current language. e.g. HTML validator, global ARexx debugger. Also has built in support for most Amiga C compilers, though it never seemed to work right with SAS/C. I never spent any time figuring out why, was just as easy to do a build or debug from a WB window.
It's worth at least trying the free demo of Cubic if you haven't already.