My vote would have to be for the sexiest, most flexible laptop Apple ever produced. Batman's laptop.
The Powerbook G3 "Pismo"
Curvy. No-slip rubberized surfaces. Good wifi reception. Firewire. Two expansion bays that you could customize to do almost anything (Superdrive, extra HDD, second battery, you name it). 1 GB RAM max, which is a great ceiling for so old a system.
The final rendition of the pre-Titanium Powerbooks, Apple got everything right before diving into the thin/squarish/minimalist design ethic.
The only flaw to it AFAIK was the old yoyo power supply. If Apple had been using Magsafe connectors back then, I'd still be running my old Pismo today. My black lab tripped over the adapter cable and sent the Pismo to our kitchen hardwood floor, smashing the display. The computer still functioned with a monitor, though, and the HDD could be accessed via Target Mode, so I did not lose any important files. Sold the unit for scrap, but i think the guy I sold it to just replaced the LCD and soldiered on. Might still be in service today for all I know.
For simple word processing or as a big-screen DVD player for my kids on long road trips, they could still be useful. If I happened on one in good condition for cheap I'd probably buy it.
No laptop was ever sexier than a Pismo.