Personally I have always found Nuka's death to be really upsetting but it didn't actually have a big effect on me until after i watched the deleted scene from Nuka's death where he says 'Well, i finally got your attention didn't I?' to Zira because I didn't fully understand that he desperately wanted his mothers attention at first...
The 'great kings of the past' talk between Simba and his father always makes me tear up
Also, am I the only person that gets upset during the 'not one of us' song? i feel so bad on Kovu when he gets attacked by all the animals and sees scars reflection in the water.