I am a huge fan of Orks, and as such the way Orks talk is a massive thing for me. A game that has bad lines without Orky character means that you wouldn't really be playing Orks. In that spirit, I think we should come up with a bank of appropriate dialogue options for when the time comes.

Here's mine so far:

REVIVING A FALLEN ALLY:
"Stop muckin' about, ya git!"
"Oi! Get back in da fight!"
"Next time I take yer teef!"

TAUNT:
"WAAAGH!"
"We is da biggest and da strongest!"
"Get 'em lads!"

"Ey boyz! Look at diz git!" - pinging a target

"DAKKA DAKKA DAKKA DAKKA DAKKA DAKKA!" - randomly plays while firing continuously

"We'z gotz space morons boyz!" "Dem poncy marine boyz ar 'ere"- pinging space marines

"Oy, We'z gotz dem zoggin spikey gitz" "Spikey boyz, ere? Grate I wuz gettin bored" -pinging Chaos Space Marines

"I see panzees! Look at dem run!" "Dem L'dar gitz are ere, zog em befor deyz run awayz again" -pinging Eldar

"Dat klicky klacky sound meenz gribbliez boyz! Get ta krumpin dem!" -Tyranids arriving

"OI I needz a painboy ovah ere...no waitz nevah moind! I'z didn't say dat!" "Bleed a bit more, or see wun of den painboyz...tuff kall" "I ain'tz ded yet! I'z feel foine reel'lee. Jus dontz kall da Dok"-calling for painboy

I would unironically like an Ork set of speech like the following, perhaps as part of a...gentlemanly...cosmetic pack, it'd fit right in with the Bad Moons.

REVIVING FALLEN ALLY:
"I say old chap, get on your feet!"
"Tally ho! we have Gitz to stomp!"
"I say, stop bleeding all over my shirt."

Taunt:

"Have at thee, ruffin!"
"En Garde!"
"Hatred originating from disreputable gentlemen is going to continually persist!"

Unfortunately, I don't think GW would ever sign off on it.

I can't think of anything to add on topic other than pointing out ork lines in Dawn of War 2 multiplayer, which I thought were great. Like an ork slugga boy killing Eldar: "I got Eldar blood all over me! It's so shiny!"

There's also this related thread made by a Dev: "Cheers for Factions and Sub-Factions!!!"

bloody good suggestion, however I think the degenerate devs will decline it

GW wouldn't even let that idea get off the ground to get shot down anyways

Just take notes from DoW Big Mek.
Its who I want my Mek to be like o3o

Dis I like, includin' da "Next time I take yer teef!" one.

I'z also like Big Mek GobMaw's ideas.
Dakka Dakka if you'z keep shootin', and all da pinging da enemies. Oy, Crusadah Humies! Get dis done!