Planet Xbox360 offer up their "top 10 video game controllers": warning, they might not be entirely objective:

6. Original Xbox Controller: The monstrous beast that was the original Xbox controller was about as scary as a semi three times too big to fit in the tunnel a mile down the road, but for some people who could actually use it comfortably, there was little to complain about. For the other nine out of ten gamers who would’ve found holding onto a fully-grown grizzly bear to be more of a comfortable endeavor, there was the S controller released a bit into the consoles lifespan. Regardless of what controller you held, there were certain things about it that just felt perfect – from the size of them to the placement of the controllers, triggers and bumpers, it all just felt right. Whether you were playing Halo, Mechassault, Crimson Skies or Phantom Crash, you used the staggered control sticks to crippling effect. In fact, many of the original tenets from the original controllers can be seen in the later design of the 360 controller, except for the single fact that they’re all significantly improved on. As well made as they were, their size is what keeps them from being fondly remembered as well as keeping them from being forgotten.

I too remember the original Xbox controller fondly, but most gamers haven't - surprising, since it was one of the first controllers that nestled firmly into the palm of the hand and didn't leave me with wrist cramps.