The one that builds Great Wall... Himeji... then wonderspams everything else.
Recent game, Emperor, Siam... two neighbors America and Ottomans. Ottos pretended to be bros, but they were build their 2nd city aimed at my capital and I knew a war was coming. Sure enough, two turns later, he said lol you die, and I went Tabarnak's sword rush on his arse. Got my four city planted on a real juicy Iron tile (9 Iron) right next to his capital, and oh my god Suleiman panicked like a bro when he saw five swordsmen pumping down at him. Said hey bro sorry for dishin' yo peace, but I would have none of it. One civ exterminated under a torrent of iron.
Then, America. Oh god. He was next to me. So close to my third city. Yet I never discovered him till I finished Suleiman. If I knew what was going to happen, I would have crashed my economy to rushbuy warriors/swords, rushed all my swords to his border and taken his capital and then that continent would be mine right there.
Instead, I was content to just handle all my happiness/GPT problems, trade with "neutral" (covets your lands) Murca and then a dozen or two dozen turns later, Great Wall! Then it was some other wonder, Stonehenge... Colossus... Notre Dame... Porcelain Tower... Himeji... Taj Mahal...
And I watched him grow bigger and bigger, from a civ that my advisor said "I'm not sure they have a military at all" to "the American Empire is not to be trifled with", each wonder quickly slipped out of my grasp. It was right then and there that I vowed that in each game of continents I play, after I crushed my first early rushed civ, if there are still anybody left, I will just rush them all to hell. There will be no more neighbors on Continents, unless they are on another continent (which is another unless I have a million goldstack and nukes and oh mai)