As the tile says.
For some manga I think it’s the covers or 3 page spreads
Anime I think it’s either the animation or the fight sequences
For manga, i really like the art and how the characters are shown and for anime, you’re right, if it’s not a good animation not a lot of people would want to watch it and enjoy it
@AnimeNerds, where you at? 
In anime, the dramatic fighting scenes are to die for. 
And some are even hilarious, I still remember the iconic scenes in the anime Jojo!
Oh I always love the like
I’ll use mha as an example
Hero: goes into a flashback
you say run stars playing
Villain: uh oh
The art!!! And the psychological affect, for sure. I really appreciate it’s cinematic feeling. Really wonderful at POVs too! :3
@AnimeNerds what else do you think is the best part of anime?