I keep confusing AmigaBasic with ABasic. They both sucked. MS Basic is just too damn slow and crashes like crazy. The only good thing about ABasic is that someone made a really good Monopoly game with it, but you still need ReloKick1.3 to run it.
If you want to learn programming, you're better off with Java for coding and PHP for scripting on the PC. If you really want to work on the Amiga, AMOS is great for graphics, but lousy for data, and the IDE will drive you nuts sometimes, especially when it corrupts your code for no reason. It's easy to use and a lot of fun, though. I never gave BlitzBasic a shot on the Amiga, but I own the PC version, and I think it's pretty good. The IDE is reasonable, and it empasizes time-based programming, which is a must if you want to evolve to a true system-level language later on, like C++ or Java.
Most Basic languages get you into really nasty habits, so you'll have to un-learn everything, anyway. I went from AMOS to C, and boy did I learn a lot in the transition. C makes so much more sense than AMOS if you want to do more than move sprites around. If only there was an IDE and interpreter for C that granted you a bit more slack. AMOS is still pretty good, though, because unlike many other Basics, it enforces variable scope, doesn't require line numbers (UGH!), and the IDE allows you to collapse procedures, which is a great substitute for having to #include everything. I wish more IDEs did that! Blitz doesn't support procedure collapsing, but it does make a shortcut list of all your functions, which makes browsing the code a breeze.
Me, I like PHP and HTML. Well, I don't REALLY like them, but they're still better than most. Perl is a nightmare. Stay well clear of it if you know what's good for you! :-)
By the way, my Amiga 500 has 9Mb ram (so that will be 512Kb Chip, 512Kb Slow and 8Mb Fast) but I have not yet encountered problems running AmigaBASIC
Maybe it only crashes if it USES fast RAM. Best not try to mustitask with it, then. ;-)