The Androids being able to steal energy is certainly a technique that makes them worrisome but the highlight for me was Android destroying the city in response to Goku's request to fight in a deserted area. Villains can be quite accommodating, Frieza gave Goku the option to fight on land or in the sky, and Vegeta willingly moved to fight Goku elsewhere, so it's nice to see one that requires a bit more force to get moving.