I disagree, each arms have their own benefits and flaws.
Does a gastraphetes out range a large Chinese siege bow of similar size - historical records to say combat range is 500 yards? Or can it out range heavier triple bow - historical records to say it can shoot beyond 1000 yards with a ~ 20lb javelin?
Can ballista out range traction catapults which have been known to be able to snipe targets on a city wall hundred of feet away. How does a tightly packed phalanx deal with stone balls bouncing across the battlefield launched by these catapults; or deal with the pots of venomous snakes or incineration oils they were known to have launched?
How well does the hoplites shield deal with these threats? It is a big question mark.
I am also reluctant of simply calling a "Chinese Army" simply as one. Chinese invasion of SEA were pretty dominant. There are hickups at different times but for the predominate period of time, SEA was a vassal to China. What I am alluring to is, the Chinese military is not an identical thing through out the ages.
The Qin was famous for their crossbowmen and siege bows known to out range contempt Chinese states. They are also famous for their Phanlex with 20~ foot spears and halberds; their defensive formations and their horse crossbowmen. The horse crossbowmen are more like cavaliers, they dismount, shoot, and remount. They are also renowned for their skirmishers, often remembered as screaming lightly armored berserkers charging across the battlefield toting the heads of their victims.
The philosophies are different too as well, the hoplite is a one man war machine which when strung together to from a phanlex is an impressive forward driver. How well did it face up to the light infantry of republican Rome - battle of Pydna? This is before the time which roman legions had full body armor, a shield larger than a buckler, a spear and a short sword.
The Qin was a unified fighting machine, the crossbowmen thinned out the enemy lines, the tower-sheild-men protected the long-spear-men where the long spear-men kept the enemy at bay to allow the dagger-axe-men and skirmishers to move in from the sides while the cavaliers move in to the rear or raize enemy camps or ambush lines of retreat.
How well can the horizontal armor of Macedonians hold up to a 20 lb dagger axe on a 15 foot pole plunging down? How well can do the javalin-men deal with the tower shields? Actually, the better question is how well do javalin-men survive a wall of arrows from cross bowmen; 300 feet is not a short charge.
Of course, like all combined arms army, you break the weakest chain, the entire army falls apart. so in a stand up fight between Macedonia and Qin, I won't be that inclined to favor either side.
But here is the thing, Qin is so much larger. the largest army fielded by Macedonia was 50,000 men on the battlefield. Qin was able to field 600,000 men at one time and keeping them in the field for 4 years. If we consider the Qin-Chu conflict, we see more than a million men deployed. The reality is, Qin can lose 200K men as shown in the 224BC campaign, and walk away from it, Macedonia lost 24K men to Rome, and that broke her back.
You start to build a strawman argument out of apples and oranges in order to be able to refute something you otherwise can not disprove?
The gastraphetes is a personal ranged weapon, not a piece of artillery. You can only compare it to crossbows, not heavy crossbow artillery pieces. Same goes for the ballista, this is the weapon to compare with the heavy crossbow artillery pieces. The gastrapehtes was built for power and not adopted for rate of shot, while the ballistae torque spring technology would stay the the hallmark of the longest range medium artillery for millenia.
Traction artillery was adopted from China because it was cheap and had a high rate of shot for an artillery piece. It did outrange handheld ranged weapons and was for example used in the battle of Mohi by the Mongols against Hungarian crossbowmen why devastated their mounted archers. Ballistae do per construction have the ability to propel projectiles with even more speed than the traction artillery. There was never any kind of mechanical artillery that outranged torque spring powered systems. The problem with torque spring artillery are the very construction and operation high costs and susceptibility to changes of humidity. That's the reason why torque spring siege artillery was discontinued in the West and the Chinese inspired traction artillery introduced (and developed into counterweight powered artillery with more range and power that Muslim engineers in Mongol service introduced back to China).
China - advantage with high and powerful rate of shot by crossbow mounted bows.
Greece - more powerful crossbow mounted bows with different energy transfer system - heavier and bulkier
Greece - torque spring artillery - longest range possible, very good anti-personnel performance and very expensive
China - traction powered artillery - high rate of shot, cheap, outranges all but the ballistae, advantages as heavier siege weapon and from behind protective covers.
I know that Chinese are proud of their crossbows and their traction artillery, but the rest of the world was not settled by clueless barbarians. It's rather an observation that enemies had little qualms about adopting good weapon systems from China, but China was reluctant to do the same. So all kinds of comparisons between Chinese weapon systems and others happen outside China or in the few cases when foreign know-how is used for an invasion of China.
I have no idea why you want to establish who would win in such an encounter based on a distorted view of Western military. At least, you could easily correct that because there is more than enough available stuff on Alexander and his army.
Alexander was one of the few guys crazy enough to pull off a world conquest and if illness had not killed him, he would have sooner or later attempted a conquest of such a great land as East Asia.
What you can see with the Macedonians are a number of organizational innovations and slight modifications of existing hardware. It all starts with Thracian and to a lesser degree Illyrian warfare, the powerful neighbours who pummeled Macedon that had cavalry and infantry skirmishers with few heavy armed on foot. The Macedonians adopted the Thracian idea of using a bronze tube to make one long spear out of two shorter spears(that could be thrown). This created the original sarissa. They regulated that the spear shaft were to be made from very tough cornel wood. Next steps were strong shields that offered the best affordable defence. Marching as a block with long spears against an enemy was just one out of many tactics. Their close combat was always supported by a barrage of staff slingers positioned behind - the Chinese traction artillery is an improved version of these staff slings. The main striking force did remain the cavalry (a Macedonian tradition since the foundation of the kingdom) that were armed and armoured like the best Scythian heavy cavalry, but without bows. Instead they cooperated with fast light infantry that commited to ranged combat. Many of these light infantry were Thracians or Thracian influenced and had a number of weapons to effectively fight close quarters with cavalry in their loose order.
A lot of these military traditions could be found by the Chinese in Central Asia that for millenia remained deeply impressed by the military commander and king Alexander (a lot of Central Asians track their ancestry to Alexander and his warriors).
The Chinese had ample chance to prove their weapon systems against the Hellenistic in Bactria system and I see no statement that one had an overwhelming supremacy over the other, but each of them had things that offered advantages lacking in the other.
Your statements show that you are not well informed about European history and armament. You mix things up. Rather ask whether the long spears of the Quin close to Central Asia could not have been inspired by the stories of the Macedonians? The mounted crossbowmen you highlight were similarly operated by the Macedonians with their very powerful weapons, ballistae and oxybeles to big gastraphetes. The Macedonians at Pydna were one of the Macedonian states facing the Romans in one battle. A whole range of conflicts start with Pyrrhus, but all these Macedonian phalanxes have evolved into something totally different from the ting Alexander had at his disposal. They had different armament and tactics and lacked combined arms and flexibility of employment. As far as numbers are concerned, the Hellenistic kingdoms became a kind of apartheid regimes with military power limited to Macedonians and Greeks who formed the phalanx that in a push of pikes decided battle. All attempts to integrate the vast majority of subjects into these phalanxes were canceled sooner or later, while during Alexander's days things were still in a flux - resulting in a much wider manpower base than the later ethnocracies. It was this system of ethnocracy that made these kingdoms brittle for destruction, because there was just one phalanx to crush in one battle for gaining an empire and these empires were so busy infighting that they all acted the same with heavily armoured pike blocks crashing into each other. The subjects, if armed, were delegated to swarms of little trained police forces and skirmishers. Rome, like Han China did not have an ethnocraty, but a system you could adopt and identify with. That gave them strength throughout all defeats against Hellenistic and Hellenistic influenced armies. Many Roman victories were close run affairs and by no means were the Macedonians reported worse swordfighters than the Romans.
