I guess at this point it's all opinions. But Bigfoot being an alien is certainly not one I've heard before.
(I don't think bigfoot exists, but I also pretty strongly don't think aliens have visited Earth, so 'twice as likely' to me is very close to 2*0 vs 0, and seems just as reasonable as it being half as likely.)
My original point is that the aliens question fails to capture belief in the paranormal or conspiracy the way the others do, and should have been specifically worded better to avoid that issue.

"Region" would have to be extremely small around here to not include someone who speaks almost any (natural) language a typical person could think of.
I'll just go ahead and answer a different question: If I could instantly learn any language and my SO could instantly learn it also, I'd pick ASL, because it would be very nice to have a way to communicate that works where talking either doesn't work (loud places, for example) or would disturb others, or just across a large room.