Depends on what you want to do. If you want to easily run all the games from floppy I would go with the A500. The A600 has a newer ROM which has some incompatibilites but you can always use Relokick.If you want a whdload machine then the A600HD is a better choice. It has more chipmem and a hard drive.You can add a hard drive and megi chip to the A500 though.The machines are pretty similar and both can be customized to make up for the differences. I would probably go with the A600 due to its smaller footprint.
