My personal favourite Amiga Model was the 1000. Simply because it was the first machine that brought the computer world to attention, and started all the later Amiga models. And, also it was well ahead of its time and miles better than the PC and MAC, with its graphics and Music capabilities. It will go down in history as a great computer system and a brilliant contirbuter to technology.
As for the worst model (dare i say it!). That would have to go to the 500+. What a waste of time (and money) that was, and all for what? 6 months! I cant see any point in it being released, it wasn't too much powerful than the original 500 and with the 600 and more powerful 1200/4000 just around the corner it had seemed pointless!