I can only agree with the other responses.
In my personal usage, I would say Abendessen and Snack.
Abendbrot sounds like something a 60+ year old would call it.
I haven't heard it called Brotzeit since I was in elementary school in Bavaria, so that overlaps with the sibling responses.
Personally, when I hear "Imbiss", a kiosk that sells food is the primary thing that comes to mind. As in, you can get a hot dog with fries there.