Here's my question:

Which conspiracy theory do you believe is the most likely to be true AND which do you believe is most likely to be false?

i have things i want to believe but there are not enough evidence like tesla superweapons exist, free energy devices have already been made, and US stole high tech from germans in ww2 that resulted to roswell ufo incident which was probably an experiment, antigravity stuff...

entertaining thoughts

Mr. Otter comes out swinging lol. 

For me there are two at the top. Kennedy/911 - both stink.

Most likely to be false- Flat Earth

False And amusing , flat earth.
Possibly true , nannup tiger , both story's .
From a town near me , a number of big cats (tigers panthers) escaped a Train that derailed and there are a small community of big cats still alive.
Or my personal favourite that the Tasmanian tiger (that's extinct) has a close relative that is undiscovered and has a very small population in the south western forests of Australia.

@Morphy,
Those sightings could be willful delusion, but I generally agree that cryptozoology, aliens, and ghost stories all have that common element of eyewitness accounts which are impossible to prove.

Personally I think scary stories are one way of hacking the brain by applying a specific form to a non-specific fear. It’s kind of the inverse of the “invisible gorilla “ effect.

Israel's 1967 attack on the USS Liberty surveillance ship was intentional and premeditated, not a case of mistaking a far smaller beat-up 1920s Egyptian livestock freighter for the most sophisticated spy ship in the world (which discovered that the Israelis had just mass executed a bunch of captured Egyptian soldiers, incidentally.)

Vaccines aren't universally safe; polio vaccines were infected with SV40 for decades, causing tumors etc. and the adjuvant components can cause the undeveloped immune systems of infants/young to go haywire and attack more than just the intended antigens, likely a factor in the increased prevalence of autoimmune disorders, allergies, etc.

Not sure what the heck happened on 9/11 but it sure as sunshine wasn't the official story, same with the death of Bin Laden who had been reported as having died 5 or 6 times prior to the "Nope we have no pictures, physical evidence, or body which we buried at sea, but seriously believe us this time!" raid in 2011.

Conspiracy theories like Flat Earth, Mandela effect, hollow Earth, and "Illuminati" (as an actual cohesive entity that is, versus a general catch-all used for convenience like "deep state") appear rather silly to me.

I do like the cryptozoological stuff, moreso with regards to rare and reclusive species not yet described versus big and dramatic Loch Ness or Bigfoot-tier claims but it's still quite interesting. If it's discovered that the bigfoots are actually members of a secretive off-grid clan all afflicted with severe hypertrichosis that would be darn fascinating too, heh.

Okay, okay... It’s been left alone long enough
@KTO, if Trump is a Russian agent, then Obama is a devout Muslim!  But if, for the sake of argument, I assume you are right, then I still can’t figure out why Vladimir Putin would want to lower our taxes 

LOL!  Well, KTO, I suppose we’ll have to wait and see how it plays out. Russia might try to take advantage of Trump’s verbal chaos, but that’s not the same as conspiring with him. I would expect Russia to benefit more from having a socialist in power rather than manipulating an election to favor a hardcore capitalist... especially one who bombs Syria and is encouraging Germany to stop buying Russian oil products. Is Trump unpredictable? Yes!  Does he say crazy things that hurt him politically? Yup. Is he conspiring with Putin to undermine America?  I doubt it.