“Simple geometry” and “Where’s your holiday spirit” are so sarcastic.
“Beer!” and “I think therefore i am.”
“Violence is usually the answer” and “I think, therefore I am”
I’m not your father!
“Bring me another” “Beer!”
-Reinhardt
I really like most of McCree’s lines. Especially because it is Matt Mercer voicing him. “I hear ya pumpkin” “I’m the quick, you’re the dead” “BUCKLE UP” 'I’m your Huckleberry"
His are my favorite to spam.
“My ultimate is …” “Mada Mada”
-Genji
“I’m NOT your father”
-Soldier 76
Mccree is my fav in that question. “Take the settle again” is so fun 
“I’m pushing the payload”
-Widowmaker
I love most of Sombra’s lines. Also, it’s hard to pick one, they’re all so much fun to spa-cough use. But from the top of my head:
Take two, and call me in the morning.
I know who’s been naughty.
Honor! Justice! Reinhardt Reinhardt Reinhardt!
Catch phrase!
Did someone say, peanut butter?
I dreamt I was a butterfly.
“Respect the chef” (It’s the respect your elders line when you have Grillmaster: 76 on)
Sombra’s boop
Symmetra’s "There is nothing that will stand in my way"
Mercy’s old resurrect lines
Reaper’s “Just win” (secretly wishes he would say “baby” at the end, would work perfectly)
Overconfidence is a flimsy shield.
Heros nevah die and 'Til Valhalla was so iconic 
Really was/is. I just went to her quote page and listened to them, got shivers ngl
“I’m on fire! but this witch doesn’t burn”
Witch Mercy. 
Stupidity is not a right
Have you ever been punched by cyberneticly engineered gorilla ? i can arrange that you know.
A really good combo with Facepalm spray/emote
“Welcome to the gun show!”
“It’s only a game, why do you have to be mad?”
-Zarya