Hard to say what my favorite part was...
I know in Ys 2 I went crazy with the gifts to make everyone really happy, and later when I discovered I could shoot everyone with fire; I had to shoot everyone with fire to hear their Oww.. ow owwww! lol
Still, the main story would have to be my favorite. The translation was error-free, well written and I finally had a chance to discover how Ys concluded...