Well I never used AMOS, but I was into Blitz pretty heavily for a while and I think it's better
There seemed to be a lot more good quality games made in Blitz than AMOS, although there were a LOT more AMOS games around.. maybe that says something about how easy it is to use.
If you are interested in more than just games, then I think Blitz has the advantage there, it has easy access to all the OS functions for writing your own apps and whatnot (maybe AMOS does too).
I don't think either is going to be particularly portable though, although Bernd Roesch has written an updated Blitz "clone" called AmiBlitz that may be available for the A1.. and come to think of it, AMOS went open source a while ago I think, so there may be someone doing something with it as well.
