I started with Ys III Wanderers from Ys on the Snes, it was a great game back in its day and I had always felt the series needed more games while I was growing up. It wasn't until a good bit into the PS2's life that I got Ys: The Ark of Napishtim. I felt the game was good for a Ys game but at sometimes it just drove me insane cause of the difficulty at times. After I got my japanese PS2 I imported Ys III Wanderers from Ys for the PS2 and in my opinion out of the PS2 remake and the PSP remake I enjoy the PS2 version better as it actually sticks true to the originals design and gameplay where as Oath In Felghana felt like Ys III mixed in with Ark of Napishtim.
I recently got YS 1 and 2 on my Wii and I haven't really played it much. Feels to me like I'm playing a football RPG but I enjoy the music. I've yet to play a majority of the games. I wanna get seven but I've always wanted to play 4. Every translated rom I can find is usually not fully translated.