My prefered Basic language
is Amiblitz2, the amiga sequel to Blitz Basic 2.
Blitz Basic 2 is good,
but Amiblitz2:
-Is 10 times more stable than Blitz2
(Never or rarely crash)
-compiles code 8 times faster than Blitz2
-Has an optional optimizer
that makes progs go 2-5 times faster
than blitz2 compiled progs.
-Is free and opensource
-Is still supported
-Is 6 times more userfriendly than blitz2
-Has (acid) command guides included
in the amiblitz2 archive on aminet
If you wanna code in basic on amiga,
then I HIGHLY reccomend amiblitz2.
It might be troublesome to get it working
on an a500 without hd or extra ram tho,
so the disk version of blitz2 by Acid
might be a better start.