Making Classic levels is pretty fun, tileset is more user friendly and less images needed for a good effect
Though, I still find IEra more fun overall, I think classic is abit more casual friendly which is probably why it attracts quite a lot of the younger players.
Era, taking a little more skill to master.. (Yes PKing on Classic isn't THAT hard really
)
Overall, more to do on Era as people have said - there goes my vote