I played 1 and 2 for basically the first time about 6 months ago yeah blasphemy I know. Honestly, I thought Darm tower was more annoying than Solomon Shrine was. But I thoroughly enjoyed playing through both! The whole game (1 and 2 together) is nice because its a shorter RPG, but not so short that you dont feel satisfied. Granted I struggled in all the usual places, on the whole it was a nice experience. And the music is top notch!
Darm Tower is pretty ridiculous, but it's so much faster in the Turbo version. Thinking back to the first time I beat Ys on SMS without any kind of guides, I'm surprised that I managed to figure everything out and even had the patience. But I always loved the game, even when I was stumped figuring out the proper order to do things early on. Part of the appeal was how mysterious the game was. I particularly loved the stories of a mysterious figure going around the land hording all the silver items.
If I could rank the PCE Ys games unbiasedly, without nostalgia, it'd go IV>II>I>III