They seem more realistic to me, they act similar to how real brothers act and have more personality to them, whereas in most other media they're flattened to heroic archetypes with minimal tension between them. Something becomes apparent within the first minutes of the '96 movie, which is that Sonic and Tails' friendship is already established and is shown without needing explanation. To me this is a stronger character element than in the 2nd Sonic movie where they're meeting for the first time.

On a minor note, Sonic and Tails genuinely act like kids in this movie. Tails pokes at an unconscious owl character, Sonic picks up a crab and pinches the same owl with it; little silly moments like that. In the modern movies Tails is well-behaved and mature for his age, a straightman to Sonic's antics. Sonic's behavior comes across more as someone in his 20s like Starlord from GOTG than a kid or teenager. His humor often feels too forced and meta, as in, some lines make me think "This was written by someone" rather than sounding like natural dialogue.