I've heard of different types of aliens, hypothetically who means us harm or who can we trust?

I've heard diverse alien species may have come incontact with usthrough out history. Different types of Greys (such as Tall grey or class A,B or C), Reptilians,Amphibians, humanoids(such as Aghartians, Antarcticans, Pleiadians etc.) mammaloids (such as Bigfoot and bear-like creatures), the Anunnaki and hybrids of us and the above.Hypothetically who means us harm? who can we trust? who has an agenda?