Does it actually matter?
I don’t think it really matters, but I picked vlemmy.net because it wasn’t too big. I figured that the bigger ones were staring down the barrel of a huge influx in traffic, so I wanted to avoid them.
I didn’t see any evidence of the admin being shady, but also wasn’t too hasty with the defederate button.
I chose vlemmy.net for the exact same reason, too. Also it was the top instance on https://join-lemmy.org/instances the day I wanted to join another instance (I was on lemmy.ml then).