Best Roman Emperor?

My vote is for Marcus Aurelius.

My choice would have to depend on the conditions they faced. Some of the “sergeant-major” emperors of the third century like Aurelian held things together though terrifically tough times. For the first century: Augustus, with Vespasian second. For the next century: Trajan, hands down. Diocletian (for all the persecutions of his age, under the goading of Galerius) built a political and defensive structure (at the price of as totalitarian a bureaucracy as technology allowed) that gave the Western empire another two centuries and the Eastern another millennium. Constantine consolidated that achievement.
The Byzantines BTW never called themselves anything but Romans (Rhomaioi in Greek). A charming story from 1912 tells of the Greeks occupying a formerly Turkish-controlled island after one of the Balkan Wars. Soldiers guarded a town square and some country children were watching them curiously. A friendly soldier asked what they were doing.
“We came to see the Greeks,” said a little girl.
“But are you not Greek too?” asked the astonished soldier.
“No, sir,” she answered. “We are Romans”.

Art:
The reconquest of Vandal North Africa was pretty much a walk, and the defense of Carthage by Heraclius in the following century delayed the Islamic conquest of Spain by a half-century, probably saving the Franks. Imagine the Religion of Peace facing off with bumbling Merovingian princelings rather than Charles Martel and Odo of Aquitaine.

The reconquest of Vandal North Africa was pretty much a walk
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See Kenneth Harl’s lectures on this subject. Institutional reconstruction in the Maghreb was challenging.
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Note, the blood and treasure expended trying to reconquer and run part of the western empire could have been expended defending the empire from threats to the south and east.

I’m with Tom: North Africa was the base from which Heraclius was able to muster strength to defeat the Persians.

The Vandal kingdom collapsed quickly. Italy was the generational battle, and the main problem there was the plague that crippled Eastern Rome. Without that, the Ostrogoths are finished by 540. Belisarius’ armies secured the entire Ostrogoth treasury, so there was no fiscal crisis from the reconquest itself.

Best by what standards? Economic standards? Military standards? The standards of 21st-century America? Seriously, think about the question of who is the worst US president. I think I would have to argue, in all seriousness, that Obama was the most damaging president, but half the public would be appalled by that judgment, and many of those who would be appalled would say the worst was clearly Donald Trump (who is admittedly flawed, but who did not “evolve” and give us “gay marriage”).

Ankylosaurus –> read again the article for which you provided a link. There is a difference between ordering and taking pleasure in the massacre of Christians at Lyons, and presiding over an Empire where such an atrocity took place. For example, Trump was President while thousands and thousands of abortions were performed. Is he responsible for them? Same with Marcus Aurelius. Consider also that whatever communication should have happened between St. Irenaeus of Lyons and Marcus Aurelius never took place. I wager that if it had, the Stoic philosopher Emperor would have seen the true fruition of his philosophy in Christianity.

My vote goes to Flavius Flav … He knew what time it was!

Constantine gave the empire, for better or worse, another almost two centuries of existence. This was time enough for the Franks. the Goths and the Celts to organize into something resembling nations to resist Islam and the more aggressive barbarians that eventually led to a somewhat secure Europe.