I agree with sticking to Wacom. I know some people who have been happy with the Bamboo, and if you are just starting out or aren't sure if you'll like it, you could do worse.
I would recommend against trying out the other brands.
I have a 6x8 Intuous 3 and I LOVE it. It has been dropped off my desk I don't know how many times but still keeps ticking after more than 2 years. I have tried the larger size but found it was just wasted space that I didn't really utilize in my style of drawing... and it was a huge real estate hog on my desk. If you use big sweeping strokes in your artwork, you may want to go with bigger, but if not, it's an unnecessary added expense.
The Intuous has programmable hot keys which can save you oodles of time. If there's any way you can swing it, it's well worth the extra cash.