The Hattrick community is colourful, it really helps expand the Hattrick world. You can find plenty of helpful managers that can help you with Hattrick and real life questions.
I am one of the old users who likes to do my own research to learn how the game works. I like that this is a thing in Hattrick. Not everything should be mentioned in the rules. I also like the federations where you can have some real tight friendships. More than some friends call Hattrick a forum, with a soccer-game attached to it.
What I like about the Hattrick community is that there are real people and you don't just compete against the computers. You play against each other, but you can also help each other in the forum and talk about everything.
I ended up playing Hattrick because I used to play some MMORPG in the past (like Dark Age of Camelot or Ultima Online) but they were totally absorbing and some of my friends described Hattrick as "easy and casual", and I believed it (lol). I couldn’t really guess, at that time, how much time and passion I would end up putting into this game.
I would say the community is the strongest reason I have stayed in Hattrick for so long. The game too of course. After having trained my players and played in the French Division 2 for a while, I started focusing on training international players to help the Moroccan team. Today 80% of the defense of the Atlas Lions was trained by me!
What I like about Hattrick is that you have to make plans for the long term. I also like the pace, that you are not playing matches every day.