A character-driven masterpiece focusing on Ben and a Highbreed commander. War of the Worlds: Pt. 1
The Perfect Pilot. It is rare for a pilot episode to land perfectly, but this one does. It instantly establishes the new status quo: a mature Ben putting the Omnitrix back on to find Grandpa Max. It introduces the alien-swarm concept, re-introduces Kevin Levin as a reluctant ally, and features the first transformation into Swampfire. There is no better episode to represent Alien Force than the one that started it all with style, mystery, and excellent pacing. ben 10 alien force all episodes top
For the completionist, here is the list organized by season, from best to "watch only if you're a purist." A character-driven masterpiece focusing on Ben and a