I think a big one – I think there’s one called an Argentinosaurus (found in Argentina!) that was longer than several double decker buses put together. Must have looked awesome. And I think it was a vegitarean so it wouldn’t eat us all.
Well…I think raptors are really cool but I’d be too terrified to leave the house if they existed so I’d say the Triceratops. It’d make an amazing pet (although you’d need a big kennel…) and you could ride it to school or work!