I think the answer to this is somewhat nuanced. For example, a lot of people here might answer gameplay, but PST is the #1 game on the codex list, and imagine a game which has great combat and exploration but the story is about a circus clown searching for his one true love in a sheep barn, would you be really able to get into a game like that? So there is a bunch of stuff to consider. How good is the story exactly, how good is the gameplay, how important are the parts that are not as good, and so on. One important reason why PS:T is such a great game is that it minimizes the parts it doesn't do well (the combat is shit but there is very little of it, exploration isn't that great but that doesn't diminish the experience), and there is so much writing that it actually becomes the gameplay in some ways (puzzles solved through dialogue, choosing which options, etc). Likewise, there are lots of great RPGs (like the Gothic games for example), which don't have the greatest writing, but it's good enough to provide the player with the motivation to play the game and let the great gameplay shine through.
We all disagree on things. I thought PS:T was very story-based. There was so much talking. And the story was weird. I was used to something like Daggerfall where you do a lot of hack/slash and of course Daggerfall was very open-ended. PS:T didn't feel as open-ended, but that's because the world is generally much denser yet smaller, while Daggerfall's is much bigger but sparser. Because there was so much more talking, I didn't feel like I was getting my fill of combat situations. Generally, I like combat, but I prefer tactial situations to be plentiful. Daggerfall's combat wasn't all that good, but I still prefer combat to dialogue. Anyway so I found myself getting bored a lot PS:T and finally quitting. I like Baldur's Gate more. It's good.
You know hte makers of PS:T said PS:T was 75/25 Story/Combat, while BG was 50/50 and Icewind Dale is 25/75--combat heavy. I recently played Baldur's Gate and felt this is true. I haven't tried IWD. I can't locate who exactly said this. Bear in mind I played PS:T before I read that, so it had nothing to do with my negative experience playing it. Because of my bad experience, I researched it. I did the same thing when I read a book and it was terrible. I went to amazon and read reviews.
I don't think I'm centrally an RPG player. To me, epic games are UFO: Enemy Unknown or Jagged Alliance 2 or Master of Orion or Galactic Civilizations or even the Battlecruiser series (if they never crashed) and the X-series by Egosoft.
I also think survival games appeal to me, like Neo Scavenger and somewhat Stalker: SOC. Some RPG-ish games like Realms of Arkania are survival-ish too, even Darklands--I liked Darklands. There's a lot of genre-blurring.
I guess I'm more into tactical/strategy survival gameplay and even some twitch than rolepaying or story.
For many years I've tried to figure out why we all are the way we're. Why're we different. Why do we like different games. It's one thing to figure out what I like, but quite another to understand why someone else likes something. I'm naturaly prejudiced to my own likes and it's easier to research them. It's harder to research something I'm not interested in. It's like having to watch grass grow. But that's how understanding is. It's not fun. Fun has nothing to do with it.
EDIT: I think I enjoyed Soulbringer more than I enjoyed PS:T and nobody remembers Soulbringer.
https://www.gog.com/game/soulbringer
Not to say I enjoyed either very much. Played both about an equal amount. Soulbringer didn't leave a bad taste in my mouth. In fact I've played it twice over the years and I still don't think of it badly. It's an older game with a funky camera and it starts hard. It's not the typical game I like, but compared to PS:T, I think I got more out of it.
It and PS:T came in the same package when I bought them.