I have found that negatives that are a little flatter than ideal for contacts or enlargements are good for scanning, but my film scanner is at least 10 years behind current technology. Its resolution is adequate. It's the density range that is probably not as high as I would like.

Another point to consider is the shape of the response curve, which may be straighter than paper. That is not as good as one might think. Film and photo paper are more likely to have complementary curve shapes than film and scanner.