Both of them were really great. They had a really nice mysterious atmosphere to it, and I don't think I can choose which is better. XD
I did actually like Kanon 2006 as opposed to the first series though, probably because of the humour of it (and the decreased chin size) XD
This season's Clannad (by the same producers i think) has been really well done so far, so if you're a fan of Air and Kanon, give it a try too >3<
So sad, but funny~ >w<
edit: I forgot to also mention... why would you torture yourself watching dubs?! >AO *wince*