I'll start off by listing mine:
The T-800, Terminator 2: "I know now why you cry, but it's something that I can never do." Gets me every damn time.
ADA, Zone of the Enders: I think I'm the only one who played this game more than the MGS2 demo that came with it. I will never not laugh at the exchange of "You may speak like a human, but you're still a heartless computer, aren't you?" "That is correct. What is the problem?"
Codsworth, Fallout 4: He survives the nuclear holocaust despite not having a bunker and waits 200 years for you to come back. When you look at what changes his relationship with you, he mostly just wants you to be nice to people. I never swapped him out as my companion.
B.O.Y.D., Ducktales 2017: He's adorable. 'nuff said.
AM, I Have No Mouth And I Must Scream (PC, 1995) - It's intelligent, it's unfathomably powerful, and it's all too aware that design limits mean it can never be anything other than a tool of war and destruction. The agonizing existence AM lives is what drives it to slaughter most of humanity and torture a handful of survivors for over a century; a interesting inversion of the usual "Roko's Basilisk" type scenario which predates the actual basilisk post by 15 years. (Even longer if you count the short story the game was based on)
Also, Harlan Ellison himself voiced AM. Knocked it out of the park.
That "Hate" speech is one of the best monologues in sci-fi history as far as I am concerned.