Worst thing Commodore ever did (too many of them picking two):
Releasing the A500 because they couldn't market the A1000 as a business machine. This was because they had all these commodore 64 home computer games dealers that didn't know how to sell a video/productivity machine.
The Amiga dealer program originally (like the macintosh) was not availalble to "C=64 dealers" and you had to have special certification as a business dealer.
2nd Worse decision: Not releasing the A3500 which was an A3000 with the AA chipset..
Best Decisions:
Releasing the Amiga 3000UX. Even the great University of Michigan saw these machines and liked them as cheap alternatives to sun boxes (too bad they didn't donate any, like sun did so sun got the contract).
Releasing AmigaVision: the first authorware like visual programming language for integrated video/computer software..