All of them are bad, except Medieval HRE and the Papacy/Vatican.
But since San Marino cannot even marginally assert the claim, I'll pick them as the worst.
The No 1. will probably make the reform rather unpalatable to many within the Aztec Empire, especially the other two members of the Triple Alliance.
As odious as the Aztec demands could be, it was relatively autonomous and light-touch system. And in case of the rest of Triple Alliance, it...
What if the Manchu still passes the Shanhai, but unable to conquer much beyond that and the Shun consolidates in a way @darthfanta suggested, resulting in a border similar to the Northern Song-Liao?
It will deal a major blow to the Hapsburg, but I am not sure if the Ottoman Empire will be able to conquer beyond the Vienna or keep it for many years. They appear to have reached the limit of expansion in Central Europe with Hungary.
It's still only around a quarter of the population (Protestant, Catholic, and the rest combined), while over half of the population is an atheist/agnostic/cultural Confucian.
No idea about how WW1 may go. So far it doesn't seem that different from OTL WW1. It really depends on how the German invasion through Belgium may go.
On the Balkan, I think Ottoman will suffer losses in Albania and North Macedonia, but I see the stalemate coming soon. The problem for...
How can they win except not fighting in Mactan, anyway? Magellan had a few dozen Spaniards and several hundred native allies, against over a thousand warriors.
Even if the Pttomans royally screw up the war at sea, what prevents them from rolling over the Trebizond's frankly terrible army?
It will probably be inevitable, but you should delay it since, as I said above, the current Trebizond army is just terrible.