IMO Hitler making a deal with Eisenhower for hidden technologies and scientists makes the most sense, especially since there are apparently more witnesses who saw him in Argentina than who saw him shoot himself.
Its not like our government was exactly driven by morals back then : http://en.wikipedia....ilis_experiment
Just a small example
Aha, now I get ya!
But let's not forget all the Elvis sightings! The sightings can't be held up as very convincing either.