My list of worst Amigas:
A600 - More expensive and less usefull A500. It had no reason to exist and brought nothing to the table over a stock 500 aside from the IDE controller. It was a game machine that rendered itself incapable of playing some of the most popular games of its time (flight sims) through its lack of a numeric keypad.
A3000 - Even with its 32bit bus, it brought little to the table over the 2000 (in fact, even after its release the A2500 with A2630 accelerator and A2091 controller were still more sought after until they were cancelled). ECS is the downfall of this machine. Its only saving grace was the A3000T. The 3000 is the poster child for the Amigas chipset stagnation. OCS/ECS were allowed to linger way too long while PCs were slowly but constantly moving toward mCGA and VGA.
My disagreements with the other models I've seen listed.
A1000 - Yea, it came with little RAM (though 256k was big in a time of 64-128k home computers) and had to be booted from floppy (Kickstart), but the advancements it brought to the table more than makeup those shortcomings. When it came out it could easily have been singing "Can't Touch This" whenever placed next to a Mac or IBM-PC of the day, most of which also had to be booted from diskettes.
A500+ I have no problem with a machine coming out the door with 2.0. I think Commodore and developers coddled 1.3 users too long which caused the OS to stagnate as much as the chipset. 1.3 users were the tail wagging the dog. For every game title they cried would not work under 2.0 there were plenty that would. They would then also cry whenever something released for 2.0+ (especially if a magazine cover disk had 2.0+ programs on it) because they still only had 1.3.
A1200 - For its size, you cant beat its expandability. PCMCIA for network cards (unfortunately only realized now with such cards being so inexpensive), full CPU slot which can take the machine up to an 060 or PPC with graphics card and HD controller options and a built-in IDE HD controller. Look at how people are using the clockport for further expansion possibilities. All in a machine you can stuff in a bag to take to Users Group meetings. I think its features fit the bill nicely for its intended market.
I cant find much fault with the A2000 or 4000. The 4000 is what the 3000 should have been so its only faults are in being delayed so long and releasing with the buggy 3.0 CPU card.