Clannad was a underdog, another steryotypical anime. It started with the same plot that countless others have adapted, it stood out amongst them.
Clever dialougue, action (surprishingly...), plot developments aswell as pre-existing relaitionships with other characters and a random encounter with a stranger made this into something addictive. YOu wont stop at ep.1, you'll go onto .2...3..4 and before you realise it you actually care what happens to Tomaya and Nagisa.
It rounds things off nicely with random plots and alot of laughs, truly one im glad to have watched.