In singleplayer I think they’re on a close level to each other. But in multi, I feel like first space crab actually gets chaotic because chicks and chickens go all over the damn place, while UCO 3 doesn’t get as chaotic(mentioning these specifically because the other crabs are totally inferior to most UCOs, maybe only the first UCO is easier).
I always believe that the UCO are stronger, as it is very fast, player who use BX will get hard with this.
Moreover, it shoot more bullets, which fly very fast, and more than the Crab