Simple, you least favourite part/place...
If i was to choose, i would probably say that the flashback in Kalm, with Cloud and Sephiroth is just getting a bit on the boring side, when i have played the game over and over again. Also i tried to skip it by going straight to Mithril Mine, i did, but after going through all the hastle of getting across, and then goining inside, my party told me "Cloud, we are supposed to be meeting Barret in Kalm, let's head back.."
What about you?