In my opinion it is necessary to watch BOTH Kanons in order to get a full appreciation of the series. So I will give my review for BOTH at the same time, comparing and contrasting what I believe to be the key advantages and disadvantages of each. I will be rating them separate however. Please keep in mind that one series is primarily drama while the other is primarily comedy. Because of this it is very difficult to accurately compare the two. Chances are that if you see people saying they liked one much more than the other, then they probably like that GENRE much more than the other.
Story 8/10
Despite popular opinion, it is actually the original story that has the better storyline. The stories of Nayuki (8/10 & 4/10) and Shiori (9/10 & 2/10) were not done very well at all in the remake. Neither was Makoto's (10/10 & 8/10) as they attempted to make her story ending seem light, happy and even cute which significantly lowered the impact of it. Ayu's story (8/10 & 9/10) was probably done a little bit better in the remake, though I liked the way they handled the story about the hair band in the original more. Mai's story (4/10 & 10/10) was obviously done better in the remake, and is the remakes biggest attraction. The main thing that the original story lacks is humor, which Kyoto Animation makes up for with interest in the remake, giving depth to an otherwise flat main male lead. The original series started slowly due to the lack of humor, unlike the remake. However, the ending was done better in the original because they did a better job with Nayuki as well as added more importance to the accidents, which the remake glossed over a bit. A nice touch in the remake is the incorporation of Pachelbel's Canon in D as a minor theme for the series.
As for the story in general, it wasn't really that original of an idea. Main male character returns to a town he lived in as a child, but he can't remember anything about his time there because of what appears to be a tramatic experience he had 7 years ago. He ends up spending part of the series trying to regain his lost memories of the time he spent there, and who he spent that time with. It's pretty much all been done before, but I strongly believe that something doesn't necessarily have to be completely original to be good. And Kanon was good, though you need to see both in order to better understand exactly what happened 7 years ago, and to understand why certain characters are the way they are. In other words Mai in 2006 and Nayuki and Shiori in the original, both Ayu and Makoto lack certain bits of important information in each series. Like it's predecessor, AIR, Kanon is at times very emotional. They don't call them "cry games" for nothing. There will be times when you will laugh (especially in 2006), there will also be times when you will cry (especially in 2002), and if you appreciate a good drama then you should find the series to be enjoyable from beginning to end. If I had to rate the overall story, then I'd probably have to rate it 8/10 for the original and 5/10 for the remake. Unfortunately the butchering of Nayuki and Shiori severely hurts my rating for 2006, otherwise it would have been 8/10. The original would have been 9/10 had Mai's story been done better. Also, Kanon had a more obvious haremish feel to it than AIR did, and had less flow between character arcs, though it didn't really affect my rating it may have if the review system worked with decimals.
Art 4/10
I don't think there can really be any debate here. The art for 2006 was much, much better than the original. The original had a very obvious h-game art style. The characters had very rough designs, though the detail was good. The backgrounds were dull and flat. Overall it seemed very early-90ish, which is a bit hard to handle considering it came out in 2002. Overall I'm being generous when I give it a 4/10. You would expect them to do a better job than they did. However, Kanon 2006 was extremely visually pleasing. The art is very reminiscent of AIR TV which is a very good thing. I love the way the background art was done. The scenery was spectacular, the skies were amazing. The attention to detail was stunning with an excellent choice of colors, color techniques and appropirately placed CG enhancement. As with AIR, the thing I liked most was the eyes. The way they combine CG effects with contemporary art to make the eyes shine like that is beautiful. Kyoto Animation gets full marks from me for art, 10/10.
Sound 8/10
The sound is pretty good for both shows, but 2006 definitely has the edge. The BGM were good for both, though I give 2006 the advantage in the theme song department. I loved Ayana's songs. Last regrets was powerful and beautiful and Kaze no Tadori Tsuku Basho was extremely catchy and uplifting. Flower and Floresence just didn't stir the same kind of emotions in me. The voice acting was good in both, the edge again going to 2006 mainly because of the one change they made from 2002 to 2006. The decision to change Yuuichi's seiyuu to Tomokazu Sugita was pure genius. His highly sarcastic tone was a perfect fit for a Key leading role. His interaction with Ayu's and Makoto's characters was pure magic. However, Makoto in episode 9 of the original was much better done than in the remake version. Overall I give the original a 8/10 and 2006 10/10 once again.
Character 8/10
The characters follow some of the typical Key stereotypes. Plenty of moé provided by Ayu (very similar character to Nagamori in ONE, only difference is Ayu's moéness) and Makoto (sort of a cross between Nanase from ONE and Michiru from AIR, similar hairstyles too, again with added moéness), the quiet and seemingly unpersonable Mai (nearly identical to Akane from ONE in personality and looks almost identical to Nanase from ONE also), the childhood friend (in this case a cousin) Nayuki (sort of like Misaki from ONE personality wise) and the seemingly cheerful girl with a dark secret Shiori (similar to Kano from AIR) and of course the highly sarcastic (in 2006 anyway) main male lead Yuuichi which seems to be a Key trademark. I made no comparisons with CLANNAD, because unlike ONE and AIR it came after Kanon and thus had no influence on the series whatsoever (even though Jun wears a CLANNAD t-shirt in episode 13 of the original series, other things to watch for are ONE's Nanase making several cameos in episode 17 and 18 of 2006 and a Moon poster seen in the theater in 2006). Stereotypes aside though, they were great. Some were done better in the original (Nayuki 9/10 & 2/10 and Shiori 7/10 & 3/10), other were better in 2006 (Mai 7/10 & 10/10, Makoto 8/10 & 9/10, Ayu 8/10 & 9/10, Yuuichi 2/10 & 10/10). Overall I rate both an 8/10. This is due to the fact that the highly humorous nature of Yuuichi, Ayu and Makoto (as well as Akiko at times) in 2006 made it easier to watch. However, the characters in the original (despite having the same seiyuu) seemed more dramtic to me and better portrayed the more serious elements of the series.
Entertainment 9/10
The entertainment value for both series are high. The original's main source of entertainment is the more dramatic elements of the story, while 2006's main source of entertainment is the more humorous elements of the story. Depending on which you prefer it will drastically affect your opinion on which series is better. Also, a lot of people tend to like 2006 more because of Mai. As I said earlier, 2006's main shortcomings arc-wise were Nayuki and Shiori, who aren't nearly as popular as Mai. It is these 2 factors, combined with the difference in art, more than anything else that I attribute to 2006's much higher rating than the original. Maybe it was because I saw the original first, but I found that the story in the original was much more engrossing than 2006. Possibly the light atmosphere in 2006 made it easier for me to take breaks while watching, but when I watched the original I couldn't put it down. For that reason, combined with the effectiveness of the drama in the original I have to rate it a 9/10 for entertainment. It would have been 10/10 had Mai's story been done better. If you like sappy, slow paced drama, then you will love this series thoroughly. Even though I really enjoyed 2006, I have to rate it a little lower at 8/10 due to the fact that certain elements that I felt were key were missing. They did a marvelous job with Mai, but Shiori's story was confusing and Nayuki was completely glossed over. So i'm docking 2 marks for ruining 2 stories.
Overall 7/10
Though I rate them 7/10 for the original & 8/10 for the 2006 version, it would actually be closer if I could use decimals. The original was more like a 7.5/10 for me. The remake was slightly better overall even though I split the category ratings 2 for each with one tied. The bottom line is; if you like drama more, then you'll probably like the original more, but if you like comedy more then you'll probably like the remake more. I tend to appreciate both roughly the same so I ended up liking both versions for completely different reasons and disliking elements of both versions for completely different reasons. In order to get a more complete story it is recommended that you watch both as the original did a poor job with Mai and the remake butchered Nayuki and Shiori. The main reason why most people like the remake more is because Mai is an extremely popular character, the art was much better and there was a lot more humor.
