Pinyin is objectively superior to everything else.
Umm, with some tweaks, Yale romanization could be just as feasible; heck, even Wade-Giles could work if there was a clearer aspiration mark than just basically copying defunct Greek diacritics, a better representation of the tones, and the phase-out of letterforms which can't be found on, say, a Vietnamese keyboard, or at least placing the vowel diacritics on the bottom à la Foochow Romanized. Cantonese, Hakka, Min Nan (including Teochew), and Min Dong could work great with a common Romanization system, even if there's a touch of old-fashionedness about it (especially for Cantonese, as the missionary dictionaries were being complied as some sound changes were ongoing even in Guangzhou itself).
As for a quieter world - East Asia in general would benefit from being quieter, as would South Asia if it was handled properly in the 19th century to reduce communal tension. Southwest Asia (= Near/Middle East) is tricky and there's no obviously clear solution to that. What would definitely benefit from a quieter world would be a more stable Latin America, if the independence forces better recognized the potential of balancing their liberal impuses with the conservative traditions by re-examining Spain's medieval past more closely. If taken to its logical conclusion, this re-examination could create a more democratic system through both a wider application of the fueros (as a balance to the liberal demand for federalism) and the existing corporate channels which served as the pillars of power in colonial society, such as the Church, the army, and the universities. A 19th century version of the Mexican PRI, if you will.