Ys games are quite fun and I think the earlier games tend to go on sale quite often too. I highly suggest Ys Origin if you want one with the retro action based system of bashing into enemies for damaging them. Otherwise, if you prefer the more modern systems, then Ys 8 or Ys 9 might be a better place to start.

The earlier Ys games take less time to finish and Ys Origin is generally just a few hours per route (I think it was about 8 hours for my first route) for me.