This has got nothing to do with anyone being pedantic. It has all to do with understanding just what is the nature of an entity which is commonly referred to as an alien.
You stated :
"How, in your opinion, are ETs most likely to travel from planet to planet?
I would imagine in a physical craft of some description."
Why would you think that aliens come from another planet? And why do aliens need spacecraft?
You see, you are attempting to solve the alien puzzle from a human perspective. Because the only method in which humans can operate in space is via some sort of space vehicle, then, this must be the only method available to all cosmic beings.
If we are astronauts, then they must be astronauts. I suppose that one might also think that these aliens must also breathe air (which planets would be suitable?), therefore those spacecraft of theirs had better be airtight and with sufficient supplies of breathable air for their long journeys.
But, maybe they don't breathe air. So how do they exist in our oxygen rich atmosphere, after landing their spaceships?
By the way, I am not ruling out the presence of UFOs on our planet, but best stick to your spaceships and your ETs and just ignore me.