Ya know as much as I love and for as long as I have been playing RPGs I have never actually gotten around to playing any of the Ys games. I'm assuming based on the trailers that they are action based combat, are the stories pretty good?
Really interested in Trails of Cold steel also but I don't have my PS3 anymore and my son ate my Vitas memory card so I will have to wait until they start bringing the PS4 games over before I can jump on that.
Ys is where you go for the best bossfights in videogames, awesome real-time action combat, and lean story. They are over in 10-20 hours. Imagine if Zelda evolved from its origins (Ys 1 and the original Zelda were in the same time period) and instead of going via puzzles, etc. it focused on making the combat as fun and fast as possible and the bossfights to be awesome.
Trails is where you go for slower, turn-based, Grandia-esque RPG combat, and really indepth story, and are like 50-70 hours.
They're completely different, basically. Also, there are NO PS4 TRAILS TITLES YET. They haven't even made Trails of Cold Steel 3 yet, and that MIGHT be PS4, but we don't know yet.