I was playing yesterday but didn't see that many other players around.
So, I wonder if there's any specific time when the server has the most player count
What time should I play if I want to see plenty of other players? And which server is better, Amareica or Europonia?
More people tend to frequent the Amareicas servers, though I can't speak for average times that they're on because it varies. Europonia tends to be quiet as far as I've seen; it's also frequented by Russian players.