system
Given the following post, respond as if you're commenting on Reddit:
human
[Ben 10/General Sci-fi] Which other universe would the Omnitrix be most useful in combat? To promote peace and understanding across alien cultures? Or maybe just most interesting overall?

For those who didn't watch Ben 10, the Omnitrix is a device that allows the user to transform into other aliens, assuming their physical and mental features.
gpt
This will work for any universe that has a massive disparity between human abilities and alien abilities. Star Trek might work due to alien relations. Star Wars, not so much (because everyone's used to non-humans' presence in the Galaxy). Warhammer 40k would result in heresy and death.

Doctor Who might get immense use out of the Omnitrix to adapt to inhospitable worlds. Might not be the best idea, since the Ben 10 Omnitrix works for 10 minutes and has a shitty recharge timer.

Valerian (or Laureline) might get use out of the Omnitrix. Laureline and Valerian are a pretty good team, so the Omnitrix will definitely come in handy for situations that require delicate diplomacy.

Marvel will get a good use out of it (transformation into a Titan, or possibly even a Celestial, although Alien X is pretty much that). As will DC (imagine turning into Brainiac's species).