I heard a roadhog spamming “That’s my- piece of cake” once. Probably my favorite combination I’ve heard 
Winston’s ‘OH YEAH’ is also a personal favorite. Nothing is more hilarious than slowly zapping someone to death and spamming ‘OH YEAH’ the entire time.
When players are gathered round, I start dancing as Widow:
“The party is magnifique.”
“The party is exquisite.”
“The party is a perfect 10.”
EDIT: Almost forgot, of course when everybody gets up and leaves:
“The party is over.” 
I like to spam Zen’s “Ones and Zeroes” voiceline when I ult because it makes him shout "LIFE LIFE LIFE"
lmao i did that once when a winston jumped me and he replied with “excuse me”
junkrat “i give it a 3” and “i give it a 10” base on what people do XD
‘I… I… I… I… I… I dre… I dre… I dreamt… I dreamt I was… I dreamt I was a butterfly’.
ResidentSleeper
just let people have their fun
Reinhardt
100% german-
and then you cut it off with BEER!
Don’t get caught with your beard in the -AARDVARK!
Or “Don’t get caught with your beard in - a poor craftsman”.
Combine voice lines. They’re great
I pick voicelines that sound like they moan at the begining.Bind it to the roll key. And when you press it repeatedly it sounds like thy’re saying “
Ah!ah!ah!ah!
”
Use fortify, spam: GOLDEN GOLDEN GOLDEN
They can have their fun, it’s not a “do not let this person use a voice line” option, it’s an “allow ME the freedom to NOT HAVE TO LISTEN TO THEM ALL GAME” option. Voice lines do not affect game play in a productive manner in any way, they can only be detrimental or benign. If someone uses one or two, I don’t care, but when they map it to a movement button, they should be banned/silenced immediately just like abusive chat.
Is nobody going to mention Rein’s “Bring me another / BEER!”?
“Oh Yeah!”
“How Embarassing”
Winston combo: “Party mode engaged!!!” then you use the dance emote
and then you “OH YEAH!! OH YEAH!! OH YEAH!”"
Lucio: "WOO WOO WOO–cant stop! wont stop!
Roadhogs laugh is long enough so if you wait til the voice line finishes everytime, it can be spammed indefinitely, without the antispam timespan kicking in.
Ana combos: are you scared? Dont be scared!!
Laugh emote+you know nothing!
Spamming voice lines is like 50% the fun you can still have in OW
Moira: Good news everyone, stupidity is brilliant. That’s the one I use and love it
Junkrat Ahh! It’s snowing! Voice line.
Spam it, he moans