His fight with Guy and his end are very memorable. I like his interraction with Itachi too. Though his backstory and personality are a bit forgettable. It's not that much a negative however, he's still one of my favorite Akatsuki.
I'm not sure how it's forgettable when Kisame was made to be an inverse of Itachi lol. Both murdered their comrades for missions and for the good of their respective villages but Kisame doubted himself and the village whereas Itachi was resolute in his loyalty.
Kisame yearned for honesty and Itachi was the 2nd best liar in the series.
Kisame was shrouded in the mist, metaphorically, and was unsure of where he was going in life. Itachi intentionally misled everyone else around him.
One is water and the other is fire.