I would say the serie being very episodic you wouldn't really be lost with any of them so it depends on what you feel like going with as some have different gameplay and systems to them as well. The stories are still connected but often more hinted at previous adventures and more focused around the current story.
If you want to go more with a chronological order though :
- Origin (hit and running/jumping with magic type system)
- Ys 1 & 2 chronicles ( Bumping system)
- Ys Memories of cecelta(ys 4 remake) (Party system)
- Ys Oath in felghana (ys 3 remake) (hit and running/jumping with magic type system) (also my personal fav but also one of the hardest)
- Ys 5 (Never released in the usa) (similar to Origin/Ys6 and oath but much earlier of that setup)
- Ys VIII (Most recent of the party system, also longest story of them all)
- Ys 6 ( Similar system as origin and oath but came out before them so not as polished, jump is bad but everything else is still fun)
- Ys 7 ( earliest release of the party system, 6 months after ys6)
- Ys 9 (Coming to usa next feb ... Party system like 8 but seems they added more verticality and more things)
So you can either go with what you feel like or go in order but either way you can easily connect the dots if you know the order of events !
I'm currently making my way through Ys 8 after putting it down when it came out for both cosplay and to go back and finish a few earlier ys games I hadn't. Now that I have 9 I am trying to go through 8 fast but I'm honestly enjoying it so much that I kinda want to get everything I can out of it. I gotta say though, coming back to it makes me appreciate it a lot more after Ys 7 on pc being a little on the jank side for me, not to mention just how much better I feel the pacing is and the combat improvements. The chapters after the prologue and 1 get a lot longer with lots of side stuff to do but they keep things fresh and moving along and a few moments in this game have really caught me off guard. I also think the game feels just so damn good to play. The only thing that slightly bugs me about the gameplay but I can't find a better button map for yet... is the guard. For 2 reasons, one being that guard button plus another button is a skill which throws me off more when I want to just guard rather than wanting to do a skill. Skills are easy to pull off but I think my main issue with this is that because of that, you have to hit guard before you use a skill and thus the animation for guarding can't stop you. The visual for it being a quick light shield looking thing really throws me off sometimes, makes it harder to time the guard altogether, which is kind of a shame when getting that flash guard just right is so damn satisfying.
I think I would have the character at least put their arms up or something, but then I also feel maybe guard should have it's own dedicated button. This is one of those cases where I really am not sure what the best solution would be for me, but maybe I'll just get used to it. Also gotta love when Ys dangles that double jump in front of you like a carrot on a stick leaving you to wonder when you're going to get it... this one is even like YEAH LOOK I'M HERE BUT YOU CAN'T USE ME YET HAHA at a certain point and it's like... damn ys, why you gotta do this to me? Give me a taste and pull it away like that.... xD
Anyway, minor nitpicks aside I am like 20 hours in and loving this game so yeah....
I just can't wait to see what happens in 9 though...