China’s big rival in the 21st century is the United States of America. America presents herself as the bastion of liberal democracy in the face of China’s brand of legalist autocracy, although her reputation is far from spotless around the world. For example, it was private American interests who took control of the Congo during the division of Africa, and while the American government eventually put an end to the excesses there, America’s reputation as the “worst colonizer” is still prevalent in Africa and one that the Chinese and Germans take advantage of. America’s support for Britain during the two great wars has also poisoned the well with Germany, leading to lasting enmity between the two superpowers. However, America’s reputation as the “freedom” alternative to China has led to its popularity among opposition groups and anti-China governments in Asia.
Britain is a shadow of its former self, particularly after it had to let go of its colonial empire, with British India going first. Much of its former colonial influence has been gobbled up by Germany, America and China. It does, however, serve as one of the last states in Europe free from German influence, although the Germans would point out that they have become an American colony in exchange.
Speaking of Germany, it was once allies with China, but the Chinese decided to ditch Germany in order to prevent it from becoming a German satellite/puppet. Post-Second World War, Germany has focused on building and maintaining its continental European empire, using Africa as a source of resources and cheap labor. Germany presents itself as the third option to the Sino-American divide: conservative, but not draconian; liberal, but not materialistic. This narrative isn’t very popular outside of Germany’s own sphere of influence.
Argentina managed to become an economic great power in the late 19th and early 20th centuries, leveraging that into political influence over much of Latin America. Although once a rival to the United States, the two American powers have since become allies, owing to their shared interest in keeping their respective spheres of influence free from foreign meddling.
The Ottoman Empire is a geopolitical isolate, aligned with none of the major powers and enjoying regional power by itself. It has staved off collapse by luck, determination, and money from its control over global trade routes and petroleum. However, a succession of corrupt leaders, from the Sultan to the lowest mayors, has transformed the Ottoman economy into one entirely dependent on fossil fuels. A few shocks in the price of oil have caused economic collapse and subsequent political instability, and while the Ottoman Empire remains intact, the rest of the world eagerly awaits the moment when they no longer have to pay for the sick man of Europe’s life support.
Quite a few surviving Chinese Empire settings seem to make the place look rather similar to the People's Republic of our timeline. They've got the massive surveillance state, the ruthless yet pragmatic leadership, even the modern and massive-scale architecture and an equivalent to Tiananmen Square. At least Hong Kong has stayed free in this world. Though the differences are there; the monarch being the executive authority over a parliament and the society's militaristic flavour give me pre-WW1 German Empire vibes. No wonder they got along.
But I do love me a Sino-American cold war scenario (and one that's been going on as long as the OTL Cold War instead of being a post-1991 thing only); a China that hasn't been beset by warlords and regime changes all throughout the early 20th century would likely rise to superpower status even more quickly than the Soviet Union did. The name of the alliance they lead is pretty funny though. Trying a little too hard there, China.
China may have been the one to break off the alliance with Germany out of fear of becoming a satellite state, though China would have been a huge tail to wag. Given the disparities in size and population, Germany is the one who should have been worried about being made a satellite.