Favorite is the A4000T. I'd still love to have one.
I was going to berate the A500+, but really that's just a cost reduced A500, so that's not so bad, it's good business.
I guess I'd say the A600 was the worst. It was underpowered and over the projected price. (it was supposed to be the A300)
IMHO, the A500+ could have held out until the A1200 shipped, saving the R&D and marketing costs of the A600.