>>1806361Sub is better. The English voice cast of Clannad couldn't even pronounce Nagisa's name correctly (it's "Nah-gee-sah" not "Nuh-GEE-suh"). Besides pronunciation, I honestly think that emotion is conveyed much better in the original Japanese voice cast.
Please note I'm not anti-dub; there are many animes I've watched and loved in the English dub version (Fullmetal Alchemist, Trigun, etc.).