I would personally recommend Ys: Origin first as it's a prequel before all the other games, has one of the best stories, good gameplay, and will add to your experience if you play Ys 1 and Ys 2 afterwards but as I've said before? They remastered them so they look better but the gameplay is "eh." Then either The Oath in Felghana or The Ark of Napishtim. Afterwards go for Memories of Celceta and Ys 7. Lacrimosa of Dana. Then Monstrum Nox. Word of warning Lacrimosa of Dana has a wonky translation.