5 good Roman emperors and 4 good Chinese engineers

Five are Nerva, Traian, Adrian, Anthony Pius, Marcus Aurelius, https://en.wikipedia.org/wiki/Nerva%E2%80%93Antonine_dynasty#Five_Good_Emperors

Before his death, Nerve handed over the power not to a relative, but to an outstanding commander, Trajan, not even a native Roman. For the sake of legitimacy, Nerva adopted Trajan. The next three emperors did similarly. Under the rule of the Five, Rome reached its maximum. Marcus Avrelius did transfer power to his mediocre son and the good epoch ended. It seems an adoptive emperor is a successful form of government. Note, that Nerve appointed Trayan under pressure from the military. Wishes of the elite were important in successive adoptions.

I will quote myself:
“So does China, which is run by a fourth engineer in a row. Great Deng was a young locksmith in France and had a job at the Creusot Iron. The current analog of the locksmith is a software developer. Deng has promoted Jiang, a mechanical engineer, who had a job at the Stalin Automobile Plant in Moscow. Jiang was succeeded by Hu, a hydropower engineer. President Xi is a chemical engineer. "

The Chinese Four differs from the Roman Five in that the new leader is appointed while the former is in full force. The result is obvious.

Peter the Great introduced the emperor’s right to appoint an heir from relatives and the 18th century was a successful century in Russia. Emperor Paul returned the automatic transfer of power to eldest son.

Can you give other examples of the appointment of an heir?
Appointments of bad rulers are desirable, my selection is incomplete and looks biased.