Ben 10 Alien Force: All Aliens' First Appearances

So, out of the 5 Ben 10 Series, which one do you think added the best alliens to the Omnitrix arsenal ? : r/Ben10

Ben 10: Alien Force (a Titles & Air Dates Guide)

The First 10 Aliens in Ben 10 - ReelRundown

The First 10 Aliens in Ben 10 - ReelRundown

Ben 10: Alien Force, Ben 10 Wiki

Ben 10: Ultimate Alien (Western Animation) - TV Tropes

Ben 10 Alien Portraits (Original Series) by dlee1293847 on DeviantArt

Ben 10 (Western Animation) - TV Tropes

Ben 10 Ultimate Alien: All Aliens' First Appearances (HD)