Kanon is a pretty depressing series, they kill off people more readily then Str.A.In ever did! In between the depressing or sad moments are lots of fun and funny moments though and I think they got a beautiful mixture of emotions to keep you going. One issue I had though is three characters went into the hospital and the main character only visited two of them and he only visited them once... when they were admitted and never in the rest of the series (I think it was about half for those two, the third one went in later and she was NEVER visited). I don't know if there is a manga, but if there is I hope that he actually did visit.
I really don't know what I'm going to watch next, I have a large selection of anime to choose from that I haven't watched, but Aquarion is coming later with Sakura Wars so it's either going to be Venus Versus Virus, Magikano, Moeyo Ken, or Divergence Eve (including the Misaki Chronicles), but I want to save that last one till later so forget that.