Sorry, but the first two links are to commercial compilers, both of which claim to produce fast optimized code.
I have no dog in this hunt, but the questions you should ask yourself before continuing to put effort into what appears to be a commercial venture is what will your product offer that these don't. And more importantly will that be enough to capture a big enough market to make the development costs worthwhile, particularly given the existence of free options (Arduino/GCC) for those chips and their accessibility to even beginners (the traditional market for basic)?