Augustus, without a doubt.

He renewed Roman civilization from the chaos of the late republic.

Hello!

And why isn`t Vitellius or Nero on the list??? No, seriously now, i think I vote for Augustus.

/Capa

My vote goes to Trajan

My vote definitely goes to Augustus. 

With peace and prosperity restored, Augustus reigned for 41 years before dying a month short of his 76th birthday. The foundation of the Principate had been set and Augustus became the model for all succeeding emperors. Tact and discretion had created a basis for imperial government far strong than could have been forged by naked power alone.

Augustus was my choice.

His political ablity  gained his control of most if not all of the officies of rome without bloodshed and hardly a fight.

One of Claudius major abilities was his use of the imperial buraucray. Through freed man that he apointed he ran the empire allthough those same freedman cause much hard feelings for him.

why Hadrian is so important for roman empire ?

But he was still regarded as a hero by the people.  My vote goes to Severus, with Vespasian as a close second.

Why isn't Ceaser on the list?

He was elected as dictator and then dictator for life, but no term as emperor. 

The word for emperor in most languages are derived from Julius Caesar's name. The Roman historian Suetonius who wrote the history of the first twelve "Ceasars" started his book with Julius. Julius Caesar commanded Roman legions and held therefore the title Imperator. But modern historians do not regard him as an emperor because the republic came back after his death and it was up Augustus to finish the job.

My vote by the way vent to Marcus Aurelius.

You guys are forgetting someone.......  Octavius was adopted by his great uncle and then took the name of C. Julius Caesar Octavianus (hereafter "Octavian"). To identify himself fully with his adoptive father and to lend his subsequent actions a veneer of legitimacy, he simply called himself "Caesar".

Then the Senate gave him the quasi divine title of Augustus which was a slightly archaic word meaning sacred or revered........and that's how he's been known through the ages.

It was his memory  that was enshrined in the political ethos of the Imperial age as a paradigm of the good emperor; although every emperor adopted his name, Caesar Augustus, only a handful earned genuine comparison with him.

My understanding of it is that the title "Caesar" was given to the announced heir to the throne.

I voted for Constantine.

I think it was a very good idea to move the centre of the state to Byzantium (and originally to divide it into two). This move probably added centuries to the life of the Empire. Conversion to Christianity was a very prudent move too. 

I also feel somehow in his debt, because I am born in Istanbul, so without him adopting it as his capital, I would probably never have been born...

I'd also mention Hadrian. I think he was good enough to be included in this list. He was a great builder. Mother once observed that in all Roman cities (mostly ruins by now) in Turkey, there is a Hadrian gate or Hadrian bath or something else built by Hadrian. So, he visited the Greeks everywhere not only in Greece.

Hmmm... Difficult. Maybe I should vote for Romulus Augustulus, though... Nah, guess I'll go for Augustus anyway. The way he ended the Century of Civil War is truly remarkable. I wouldn't know if I'd call him modest, though. Maybe just prudent, seeing the example set by Caesar. Also, he may not have been the greatest commander, but he knew who to choose to replace him (well, except for Varus...) Indeed, we must certainly not forget the great impact Augustus's reign has had on literature. At least half of all great poets and prose writers of Golden Latin are from Augustus's reign and were under his cultural umbrella: Horatius, Vergilius, Ovidius and Livius are the most famous examples.
I agree Aurelian did an amazing job, too, but we don't know what he'd have done if he would have had the opportunity to re-organize the Empire. Maybe an Aurelian-Diocletian combo could beat Augustus...

Oh, btw, Hadrian (re)built the Pantheon, not the Parthenon

TRAIANVS

I would rather say that Pater Patriae means Father of the Fatherland"

Trajanus Decius?

I as referring to Imperator Caesar Gaius Messius Quintus Traianus Decius Pius Felix Invictus Augustus, while Ihsan was referring to Imperator Caesar Divi Nervae Filius Nerva Traianus.

They are all great emperors, and I'm not picking this one as my favorite, but I like Gordian III. He was a very young emperor, and even if he was assassinated early on, he scored a lot of successes against the Sassanian King Shapur I.

All I can say is COOL!  

My vote goes to Hadrian because he simply was an astonishing leader...and after i have read his biography i find him the greatest emperor of all times...or maybe Theodosius or Augustus was greater...

And i think Nerva should be in the list also?

Something should also be taken in consideration too on the decline of the Roman military. It didn't simply bang happen. Over the years of excessive taxation, decline in value of money (therefore reducing trade), and the tremendous effect of the plagues sweeping the Roman Empire, affording the military became impossible. So we also need to search deeper into what caused the decline of the military before we simply assume that it was the cause of the military's decline. Everything that caused the collapse also linked to another thing. For example, the military decline resulted in mass invasions by both the barbarians, and also by the Sassanian Persians.

Just to be accurate, he wasn't baptized until in his deathbed, which was a common practice at the time. When he 'converted' could be seen as a gradual process over his lifetime (due to political necessity or, that it took a while for him to understand the religion)

Blaming Constantine and his subsequent adoption of Christianity as the state religion doesn't take into consideration that the 50 years following the murder of Alexander Severus were one of the lowest points in the history of the Roman Empire.   Severus was murdered only 70 years or so before Constantine.

The troubled times led to a succession of short reigned emperors who far more often than not met a violent death usually at the hands of their own troops.  The empire was basically fighting for its life and was being threatened on almost every front - a resurgent Persia in the east and the Alemanni and Goths of the Rhine and the Danube.  Its during this time we see the first emperor to fall at the hands of the enemy and the only emperor to be captured and die in captivity abroad.

This was a time when the empire temporarily split into two parts - The Gallic Empire and the Roman......and it wasn't the congenial split of East and West.   There are emperors that we have little or no information on because there's little more than a name in the historical records.  Of one emperor - Aemilius Aemilianus - Eutropius wrote "Aemlianus came from an extremely insignificant family, his reign was even more insignificant, and he was slain in the third month."

The seed for the fall were sown long before Christianity rose.