I'll just write about RPGs, otherwise my post would become even longer.
I have a hard time replaying RPGs because I've already been grinding for hours and hours, and I don't want to do it again. Combat isn't good enough to inspire another playthrough. Also, most game stories don't manage to surpass mediocrity outside of a handful of really memorable moments. But the biggest reason for story not being worth another playthrough is it's d r a g g e d out. Way too much mediocre combat to string together cruelly small chunks of story. Awesome characters can save an RPG, but they still suffer from the same problems stories have of strung out and brief moments to shine. Reaching yet another mining town with a monster problem in the breadwinning mine sure kills my motivation as well.
My most replayed RPG is probably Super Mario RPG (still only about 3 full playthroughs and a half dozen partials), because it addressed both those concerns: Timed blocking and striking single handedly made the combat SO much more fun. The story isn't mercilessly strung out; the game is a good length and the story is charming. The characters are adorable and have a fair amount of time to shine because once again, the story isn't strung out.
Mario is kind of an exception though, I really have a hard time maintaining interest in RPGs long enough to finish them, much less replay them:
-Star Ocean: The Second Story: one completion, one 50%. (This mixed in positioning and ARPG combat with traditional combat, that helped a lot)
-Final Fantasy 10: one 60%, one 95%.
-Final Fantasy 8: three or four 50-75%.
-Final Fantasy 7: one 10%, one 30%, one 90%.
-Star Ocean: Till the End of Time: two 80%.
-Breath of Fire III: one 40%
-Persona 3: 10%, Tartarus is SO boring. Why randomly generate your dungeons!? I hate Tarturus; if you could skip those parts and just do the social stuff, I'd do it! No, I don't think the weakness knock over 1 more mechanic is enough to make the combat not boring. I'm sorry, I wish I liked the game, I keep trying but it's so painful. I could stomach this combat when I was younger, but I'm so tired of it now. On the other hand, I completed Cthulhu Saves the World, why am I so flippy floppy?
I don't replay, but I do tend to play through the beginnings of some games quite a lot. For example, I love the first 2 hours of Half Life and Half Life 2

(have never beaten the former, and have only once finished the latter).
I do have a high tolerance for certain varieties of repetition though, just not traditional-ish RPG fighting. (The original) Fable's combat was always fun for me, even if it is repetitive too. I also like RPG combat that's like Baulder's Gate or Final Fantasy Tactics. Just can't stand the traditional style.