I knocked both Ys I & II out over the weekend. First major exposure to Ys, previously I'd only sort of dabbled with it or admired from afar. It left me wanting more, which leads me to my question: is there anything like these out there? Especially something like Ys II.
I've played a few hours of Origins, Felghana and Seven before, and actually went straight into Felghana after finishing II, but the feel of them is different. While I quite enjoy the minute-to-minute gameplay (though it's not quite as satisfying as bumping, surprisingly) I feel like the boss design in the modern ones is completely different and to be honest, probably a little too hard for me. Where Ys and Ys II's bosses were generally a case of figuring out patterns and timing, most of the bosses I've encountered in the more recent entries seem to throw out different things at random. There's an appropriate method to beat each, but instead of a timing and pattern memorization problem it feels like it's more of a reflex problem and I feel like I can't keep up. Maybe I'm getting old? It isn't to say I don't enjoy them, I just feel like I & II really clicked for me where the newer ones don't as much and that seemed to be the really major point of difference.
I guess you could say later-series Ys bosses are more about reflexes, but they're still largely based in pattern recognition. You're generally given ample time to react to a boss' attack patterns, you just need to learn HOW to react to each one. Every move has a tell, and every tell is given well before the move is executed.
Of course, I am speaking of Normal difficulty, and would strongly second the suggestion of toning the games down to Normal or even Easy if you're having trouble with them -- that's what the difficulty level is there for, after all.
Ys Seven and the upcoming Ys: Memories of Celceta might also be more your style -- they're both much more forgiving games than previous entries, but still just challenging enough to keep you on the edge of your seat from time to time.
If you really want to play another game like Ys I & II, however, there is one other bump system Ys game, and that's Ys IV -- or "the Ys IVs," really. Hudson's "Ys IV: The Dawn of Ys" on PC-Engine/TurboGrafx-16 CD is probably just the thing you're looking for, and while Tonkinhouse's "Ys IV: Mask of the Sun" on Super Famicom is also a bump system game, it's a very different experience (different story, different dungeons, and sadly, 4-directional movement only), so it's not QUITE as highly recommended -- but might still work for you in a pinch.
Both games have been fan-translated, and Dawn of Ys is honestly one of the best games of its era that I've ever played, so it's definitely something worth looking into, I'd say.
...But if I were you, I'd also give the newer Ys games another chance. Napishtim, Felghana and Origin might work for you on a lower difficulty setting, and Ys Seven would probably be totally fine for you as-is.
-Tom