I know that most "Programmers" don't care about Amiga anymore, so it is harder to get questions like these answered without a lot of off topic opinion, or sarcasm, but some of us still want to learn and program for the Amiga, as we are not looking at it as a way to make an income
Some of them, perhaps but not all. I'd love to actually have more time to indulge the more experimental side of programming on the amiga but I don't. I had a lot of fun mixing stuff together that would give some puritannical coders apoplexy (ANSI C++ with assembler was always good fun).
BASIC languages are good if you want to knock something together quickly but I honestly feel that they can restrict what you learn in the process and teach bad habits that you might find it hard to move away from.
The best all-round programming language for the amiga is probably C but that's not to everybody's taste. I would still recommend it if you are looking to progress beyond the odd bit of dabbling. It's also a lot better supported than most BASICs currently available.