Who was the best Roman general?

[NikosMaximilian]

Roman general Flavius Aëtius

He was one of the last Romans(a real roman) to actually defeat Attlia the Hun at Chalons.He was a proper leader,and at that time could have bought rthe old legionary army of rome back.Except I think he died or was mudred.The western roman empire at that time was so weak,only the east could have surived.FLavius would have been fit for a emperor ,the first thing he would have done is after defeating attllia,he should have taken power in rome,then he needed to drive back the germanic tribes prouling gaul and spain.He'd then go to the eastern roman empire,defeat the eastern emperor,and unite the empire,Then in the east he would wipe out the enemies there.He'd then reorgainese rome,bring back the old legionary army of rome ,and Rome would have established its power again once and for all.

Of course ,this never happened in the first place.:(
As he was assianted by the foolish roman emperor Valentinian.Had Valentinian not done this.The roman empire had a chance of striving much longer

I'm sorry, but you are ignoring many factors outside the military field in your hypothetical scenario. Flavius Aetius won the Battle of Chalons by forging an alliance with Alaric, the King of the Goths. The alliance grew out of desperation: by that time the Western Roman Empire armies were nowhere near the legions of the past. A great percentage of the army was compossed by Germanic soldiers whose loyalty was divided between Roman gold and their own warchiefs. These troops weren't an organized army, they resembled more of a warband, so their discipline, organization and loyalty were inferior. The equipment was of poorer standards too: the Empire was in a bad financial situation, so there were less state provided shields and swords, and they were of worse quality.

Also don't forget that after the Catalaunian Plains, Attila didn't go away and invaded Italy. The only thing that stopped the Huns was the sudden death of their leader, who united several nomadic confederations.

I think that your claim that if he had proclaimed himself Emperor, he would have driven the Germanics out of the Empire provinces, is also wrong. The Empire was heavily dependant on foreign troops who sometimes responded to the Germanic warlord, sometimes to the Roman (promises of) gold and lands. There was no practical standing army, and the recruitment pool in the Western provinces had dwindled in the last hundred years, because of many factors (demographic crisis, climate change, loss of African grain, de-urbanization, invasions, etc.).

A realistic "what if" point for those who are interested in the survival of the Empire would the the Third Century Crisis, where the tide could have been changed. By the fifth century, there was no going back. Even if Aetius managed to beat migration after migration in the battlefield, the economic and social changes had sealed the Empire's destiny. In this scenario, my wild guess, is that it could have lasted a maximum of another 100-150 years but with its powers and territories greatly diminished. There are some other key moments that could have slowed down its fall like the reign of Constantine, Adrianople, the crossing of the Rhine, the first sack of Rome (its importance more about the message sent to the rest of the territories than the sack itself).