I have no doubt about the phenomenon and they DO exist. There are too many people/witnesses and too much evidence for them not to exist.
Look at Bigalow, the billionare. He has invested just about more than anyone into this subject and he is convinced...
I have seen unusual things in the sky on two occasions. One of the best accounts with is very interesting is the Alsagash sighting/abudction! Well worh looking into.
I have to say though.... Secure Team 10 are a bunch of frauds - Fake and doctored reports and sightings... Beware!