Six months ago, I owned zero Ys games and hadn't played any of them seriously. Now I own eight Ys games and have beaten four of them. New obsession for the latter half of 2013 (first half of 2013 it was Persona 4).
So I've beaten Ys I, Ys II, and The Oath in Felghana on Steam, plus sunk roughly a dozen hours into Ys vs Sora no Kiseki: Alternative Saga. I own Ys Origin, Ys Seven, Ys: The Ark of Napishtim (PS2), and Ys: Memories of Celceta. I don't own a Vita, so Celceta will have to wait, but I want to start on either Origin, Seven, or Napishtim soon. Which do you suggest?