Years ago I was on the chilled-is-better side. Now I am on the room-temperature side. I think the flavor is obscured a bit by the cold. Also, if the rest of it is hot, as in the open-faced toasted cheese sandwich I described above, I don’t want it cooling off the hot part.
I do still prefer salsa to be chilled, however, even when I put it on something hot such as a hot dog.