Saiyan Saga
Honestly, only thing that comes to mind his the first episode with Raditz and the old man lol
Namek/Frieza saga
This is the most I remeber from DBZ, the whole Ginyu force mini-saga I remember quite vividly, actually like I just watched it yesterday, the whole Ginyu and Goku switching bodies and Gohan being confused as f*uck lol ahh sweet memories right there.
I remember one time new episodes were going to air on Monday (where Goku comes back from that healing thing) and I was like 6 or 7 and that time, and my Mother bless her took me cloths shopping with her straight after school, DBZ used to air at 5pm in the UK and I remember one shop had the time and it was 5.15 and I was almost crying

Goku going super saiyan- I just rushed back from the toilet, too see Goku ready to transform with the epic music (I had missed Kuririn getting killed) and I was in awe when he did it lol still remember getting goosebumps and all.
Andriod/Cell
Honestly, only thing that sticks out is Goku's sacrifice (I cried and I remember my cousin making fun of me, she werent into DBZ so she didn't understand, that's what I said in my defence lol)
BUU
We had a problem with our cable company as they dis-banded and got tookover and thus I lost Cartoon Network for 3 months
and flicking channels one day I came across CNX! who were airing the fusion saga and that's when I caught up and I still remember the scene where Buu turned Vegetto into coffe candy lol
Well, those are my most vivid memories, obviously some scenes here and there I remember, but I am curious to here other people's anecdotes shall we call them lol