Zuko and Toph are pretty cool as well. Although Zuko is a tad too whiny for me. Mai is... OK but doesn't have enough screen time for me to really tell.
Even the deadliest of machines can be disarmed and disabled by the most harmless... Actually, there were many cases where mice would chew and gnaw on the electrical wiring in many of the tanks. Anyway, on a completely unrelated note