All the video games blizzard makes specially Starcraft 2 and Overwatch. They just seem to not struggle in lag department as other games. And for the massive world World of Warcraft it keeps state amazingly compare to other mmorpg's. Plus the networking seems to be a step above most.
WOW is dead simple TCP with smoke and mirrors.
Is it though?
https://us.battle.net/support/en/article/300479
My understanding is the best video game netcode tends to rely upon UDP for gameplay, TCP introduces way too much overhead to keep gameplay at its smoothest: far better to use UDP and get latest player data as fast as possible, lost packets be damned.