BASIC is terrible!
Sure it gets you started, but it also encourages a lot of bad habits. At least, every BASIC i've ever used does. AMOS in particular is dreadful from a language design point of view, although you can produce some interesting stuff with it.
A decent C library would be brilliant (assuming also a decent toolchain) although i would really miss the extra features that C++ brings to the table. That's what i'm thinking about, modern programming paradigms, object-oriented and functional programming features.