Hi, I've been looking for a good multi effects pedal and have gotten stuck in the decision between the boss gt 6, 8, and 10.

The price range for these pedals are(used on ebay):
$150-200 gt 6
$175-250 gt 8
$300+ gt 10

I was just wondering about what everyone thinks and whether its justified to drop the extra money for the gt 10. Also is there much of a difference between the 6 and 8.
I am also open to any other suggestions for pedals.