Difficult decision. In both languages, all screams are rather well acted and have some funny variations (e.g. Max the Cat: MEEEEEEEOW!, Werewolf: OUEN-DAWOOOOOO!) The single syllable in "Help" can be more appropriate to convey a sense of urgency, but the three syllables in "Ouendan" make for a nice buildup.
Hmm...I suppose Ouendan wins by a narrow margin, but only because the characters are calling specifically for the Ouendan, while the Agents seem to "spy" on anyone shouting for help in general (Hello Big Brother Khan
)
However, I like
neither when anyone in this site uses them to ask for assistance in something. I even wrote an Editor Tip about it.