A chinese water dragon. I have one, and she's the most lovable and intelligent pet I've ever owned. She's actually about as smart as a cat, almost the same amount of personality, expressiveness, but unfortunatly just about as trainable as a cat too. She does what she what wants.
Bearded dragons are similar in intelligence and personality, but water dragons seem just a tad sharper IMO. They're also prettier and more exotic looking. At first glance, they appear to be baby iguanas, but several details are different. One of the most obvious ones is their big bright golden brown eyes that make them seem puppy like, or like a cartoon baby dinosaur. Iguanas, like most other lizards, have little beady eyes, making their stare seem dull. Water dragons just seem to have so much more curiosity beaming out of their eyes too.
They are high maintainance though, and I don't recomend them as pets to anyone that can't commit to building an acceptable habitat, and clean their water every day.
I also was going to suggest a monkey. I want one actually, but I'm not sure they'd make the best pets, or else they'd be more available as pets here in the states. If I were rich and had a jungle for a back yard, I'd get all kinds of monkeys.