Odd, but I felt nothing for Kushina nor Minato's death. I mean, I knew they were going to die/were dead before so it wasn't a shock. And I hardly got to know their characters. I still have yet to see much from Minato.
Obito's "death", Gaara's childhood backstory, Jiraiya's death and Kimimaro's backstory. I didn't really find Kushina and Minato's deaths sad at all, didn't even like those chapters.