Yeah, I love the Ys series. I have many, but not all of them. I have the first one on Master System and the one on Genesis and the ones on PSP. It was a pretty clunky series untill resently. I've never heard of Legend of Heroes. What kind of game is it, an Action Adventure like Ys or more of a standard RPG, strategy, etc.?
The old Ys games are pretty retro, I played Ys1&2 PC-Engine version and it was good for its time but definitely feeling the age now. The SNES games were also pretty simplistic. They started changing it up a bit in their PC era with 3D, smoothing out the game systems and making more complicated battles, but it still has the same heart. It's hard to believe Falcom has really changed so little at its core since the 80's, in a good way unlike certain other big Japanese RPG developers who have changed far too much.
Legend of Heroes is more of a standard RPG than Ys, the battle system is sort of hybrid between your regular turn based and also strategy RPG system. There is grid based movement, weapons have various ranges, spells with casting time and area effects, but there aren't things like bonuses for hitting in the side/back, terrain and height calculations, or friendly fire that's present in some other SRPG. Here's an example illustrating the battle grid:
Legend of Heroes is also very story and adventure focused with a lot of text compared to Ys. Unlike Ys the games they don't all follow one guy's adventures, instead with stories continuing across various numbers of games. 1&2 were a set, 3-5 were another story, and now the latest five games starting with LoH6 (third chapter shown above) are a new series that is still continuing. I think the sheer amount of text combined with low overseas sales is a barrier to localization at this point. Falcom's writers do an excellent job though.