Kanon 2006 was awesome, I liked it very much, but Ayu didn't seem like the best choice.
AIR made me fucking depressed for a week.
Clannad was a godly masterpiece, my friend tricked me into thinking that after Ushio dies the anime ends, so I brutally prepared myself for that, completely unaware of the
end. I was so fucking relieved, and hands down the best visual novel based anime I've ever watched. Hands down. The two animes I would watch again if my anime memory was erased would be Clannad and Code Geass. It's also the only anime that has ever made me tear, and it did it