I've got a medium sized Intuos 3, used an old serial/ps/2 Graphire before that, have tried a Cintiq 12WX and a Bamboo recently.
If you're doing heavy graphics work then pick up a Bamboo, it's a jaw-droppingly lovely Wacom tablet that's not obscenely expensive and will afford you a good few hours of sketching fun in photoshop before you get bored of it. It's also a good combatant to RSI (repetitive strain injury). If you get pains in your mousin' wrist you can switch to using the tablet.
The AipTek MyNote is also quite an interesting sort-of tablet. It works as a very basic graphics tablet when hooked to a PC, but it can also be carried around separately with a wedge of A4 paper clamped to it. You draw on the paper with a special pen and the tablet will digitize what you draw in real-time. Grabbing the files off the tablet and converting them to vectors for editing in illustrator is then trivial.
I wish the Cintiq was affordable. It's the badgers nadgers to use.