Was the Roman Army the most effective fighting force pre-gunpowder?

[Alexand96]

I'm glad that you're pro-Roman - so am I. However, I do thinking you're perhaps a bit too emphatic with your defense of the Romans in this "what if?" scenario. Obviously, I'm sure you're aware that simply swapping Pyrrhus with Alexander, or declaring that Alexander only went East to fight Persia because "he knew Rome was too strong" is beyond ridiculous. Alexander was destined to go after the Persians long before he was born. One honest question to settle the point - why did the Roman warrior class constantly honor and compare themselves to Alexander throughout the entire empire above all others?

And Hannibal was obviously no slouch either; personally I don't know who I think is the best commander of the big three in the Classical world (I'm including Caius Julius there). Rome defeated Carthage, but at great cost, and over generations of war. 

Getting back to the question at hand, I personally think it's worthwhile to choose a specific Roman commander and army before proceeding. Who do you think would crush Alexander or Hannibal? Who would crush Attila, Ghengis Khan, or Charlemagne? Even if we're just trying to have this discussion for fun, saying "Rome > everyone else" is too vague. Personally, I'd vote either Caesar or Scipio Africanus as the greatest Roman commanders/armies of all time.