Alright, I admit the combat can't hold a candle compared to Fallout's. That's a little to due with FO's combat being one of the best turn based sytems (let me know if you think there's a better one) and PS:T's poor quasi-click fest.
But that's just one aspect of the game!
FO's music is awesome, but PS:T's is more epic and probably edges it out.
But it comes down to the story: Yeah, FO is more open-ended and PS:T seems almost linear in comparison (although relative to modern RPGs is pretty open-ended). I do like the way FO doesn't cram the story down your throat, but leaves it there for you to discover - complementing the gamer's intelligence. But PS:T tells a magnificient story more intricately than most mediums. I guess it's the writing. Yeah, it's gotta be the writing.