One thing that has always fascinated me is the fixation on the repetition of alternate history with OTL history. The rise of English naval power, the stagnation of the Ottoman Empire, and the fall of the French monarchy are some discussed. Italian and German unification are seen as something that was bound to happen when it was much more likely not to have occurred (failing in the same way the Arab Spring did). Along with this, we have a focus on popular myths, such as the Black Legend of Spain, the Protestant work ethic, and the tolerant multiracial and multireligious Al-Andalus (by the way, what is this fixation on transforming North Africa ethnically into the Congo? From Cleopatra to Hannibal, the US depicts them as black, where are the Berber/Tunisian actors?).
By the way, the Ottomans, despite being heavily criticized, are the most significant Islamic empire. Without them, I would say that the Islamic realms would have had a very difficult 16th and 17th century. Now, regarding the African kingdoms (sub-Saharan), we basically have three strong centers: the Horn of Africa (with Ethiopia being the most interesting in my opinion), West Africa (especially in the Gulf of Guinea), and the Congo region (with the Kingdom of Congo). They are usually fairly represented in alternate histories (sometimes the author exaggerates in a clumsy way, like Ethiopia winning a naval battle in the Atlantic against Portugal, but apart from that, they tend to be well represented). Besides that, there's a rather peculiar issue that can't be resolved, which is the Anglo-centric view of the problems (After all, the site is in English, and I imagine that the vast majority of people are from Anglophone countries). So, we have a certain tendency for England to go Protestant and the USA to exist (along with the UK rules the waves).
Another thing that I've read more than once is that until naval technology advances enough, a coastal/ Mediterranean navy is irrelevant on the open sea, and the same goes for an open sea navy in relation to the Mediterranean. Some countries like Spain had so much money that this wasn't a problem, so they could fight in the Mediterranean against the Ottomans, France in the Caribbean, England on the coast of Ireland, and triple the army without major issues (well, outside of the semi-economic implosion in the future). But without access to this money, it's not feasible. Another thing is that rich colonies/large empires don't necessarily mean developed kingdoms. The Mughal Empire, Manchu China, Tsarist Russia, and the Ottomans were all gunpowder empires. They had technology but couldn't keep up with the technological advancement of smaller countries (like Belgium). Russia managed to dig itself out of this hole of partial advancement, and the Ottomans almost did. Modernization and Westernization were a crazy and difficult process to succeed. Egypt tried and ended up trapped in eternal debt (as did most that only achieved partial progress).