Here is a custom-sortable list of every missile unit in EB 1, containing info on their range, missile attack, ammunition, and recruitability as of turn 1 starting positions on the campaign map.
No commander worth their salt can overlook missile units. They are so important in this game, particularly on the higher difficulty settings. And indeed they have been crucial in the real world too, to the point where modern warfare is conducted with essentially no melee combat at all. It's all about missiles in the 21st century. The importance of missiles is simple: it's always better to shoot your enemy safely from a distance than it is to engage hand-to-hand with them. Missile units maximize your kill/death ratio because they do not need to put themselves at risk of death in order to make kills, unlike melee units. Therefore, it is important to know what your best options are as an EB player in regards to the use of missile units. The purpose of this thread is to provide the reader with some information to assist in making those decisions.
Note that no javelin units are included on this list, because firstly javelins are all short ranged and nobody should need a guide on how to win a skirmish against javelins - just don't go near them, shoot them from your maximum range. If, as I said, the whole point of missiles is the ability to make kills on the enemy without exposing your soldiers to risk, javelins fail on that all-important measure, because they have to get in so close to the enemy to fire their missiles. They can't very well make kills without putting themselves at almost as much risk as a full frontal melee assault, which is their biggest downfall as far as missile units go.
Second, and more importantly, javelins are of such poor value. No javelin unit in the game has enough ammunition to take out an enemy unit completely, unless you manufacture some wildly unrealistic situation like shooting the most lightly armoured enemy unit imaginable, directly in the back from point blank range with a considerable high ground advantage, when they are in tight formation. The only thing javelins are good at is taking out elephants. Aside from that javelin units are only useful when they have a function other than merely shooting javelins - like the heavy infantry fielded by Rome and by the Greek factions, or Numidian Nobles and Tarentine Elite Cavalry; i.e. troops where throwing javelins is only a sideshow to their main ability. Specialist javelin skirmisher troops are among the weakest in the game due to their crippling tactical limitations, and therefore do not merit being considered in this analysis.
With that out of the way, let me offer my analysis based on these statistics as well as my considerable experience in using and going up against these units.
1. Saka Foot Archers are the best archer units in the game. They outrange the vaunted Cretan archers, as well as every other non-artillery missile unit in the game, meaning they will always defeat a unit of Cretans by virtue of being able to get a volley off before the Cretans can respond in kind. Of course this is ignoring considerations like armour upgrades and high ground/low ground scenarios, we are talking strictly about unupgraded units on perfectly even terrain standing 300 metres (or whatever unit of measure the range is calculated in-game) away from each other at the start of the battle. And moreover, the Saka player can recruit them from every single settlement in the game, making this particular unit an incredibly overpowered option around which to build an army.
The Cretans are however the 2nd best archers in the game, thanks to their range which betters all others except for the Saka Foot Archers, and their high missile attack, which together allow them to outpower as well as outrange all other competitors. The major drawback is that aside from mercenaries, they can only be recruited in Crete, Antioch, and Alexandria, making it more difficult to mass these units and build your army around them as the core missile troops.
An honourable mention for the Heavy Persian Archers, who have excellent range tied for equal-third in the foot archer class, a good missile attack value, and their good armour which should allow them to beat most other foot archers easily and even compete against the Cretans and Saka Foot Archers.
2. Artillery weapons have excellent stats but are wildly impractical due to their prohibitive recruitment and upkeep costs, and their reduced movement speed on the campaign map also makes them much less viable in single-player. There's no point in recruiting a fantastic unit if it can never get to the battlefield in time. Moreover, their low unit numbers, lack of any melee defence and armour also makes them a poor choice, as an enemy or human opponent can easily deal with them by shooting them down sacrificing a quarter-unit of low-value archers in exchange, or rushing them with light cavalry. It only takes a few volleys from an archer or slinger to destroy an entire unit of artillerymen, in which time you're not going to make too many kills on the enemy and those that you do make are low value. Artillery also tend to be inaccurate, meaning that theoretically a horse-archer unit moving around rapidly can take out an entire artillery corps without losing a single man.
3. Rhodian Slingers are the best anti-heavy cavalry missile unit in the game. Slingers in general, as we all know, are a fantastic counter to heavy cavalry. They're very cheap, very expendable, widely recruitable and therefore easily massed and easily replaced, and best of all, if you get three or four slinger units into an army they can be absolutely devastating against even the most heavily armoured enemy horsemen. Rhodian Slingers have all these attributes, but also have excellent range, outranging all other slingers and allowing you greater flexibility. Their only drawback is their recruitability as they can only be trained at Rhodes. This means that in practice on single-player Hellenic Slingers and Eastern Slingers are just as good as Rhodian Slingers, even if they will lose to them one-on-one and even if they require better micro skills in the subtle art of sniping enemy cavalry without being rushed by them - because you can pump out ten times as many Hellenic/Eastern Slingers per turn than you can Rhodian Slingers.
4. Early Saka Nobles are the best light/medium cavalry in the game. As far as horse-archers go, these are truly world class, thanks to their unsurpassed range which equals that of Cretan foot archers, and their excellent missile attack, which again equals the Cretans. On top of this they are well armoured. So, Early Saka Nobles should be able to win a skirmish against all but the heavy horse-archer type units, thanks to outranging, outpowering, and outarmouring all the other light/medium horse-archer units in the game. In addition they are very skilled in melee and able to go toe-to-toe against all but the heaviest of enemy cavalry in hand-to-hand combat. Think of them as if you could combine the qualities of a Cretan Archer, a Heavy Persian Archer, together with a Persian or Arabian Archer-Spearman, and put a horse under them. They are just monstrously overpowered.
An honourable mention in this category goes to the Roxolani Riders, who aren't as good as the Early Saka Nobles at any of those skills - archery both range and damage, armour, melee combat ability - but they are fast moving, an attribute which can be very valuable in itself in certain circumstances. Roxolani Riders are also superior to every other fast moving horse-archer, they are at least their equals as archers while being more armoured and better in melee.
5. Sarmatian Bodyguard is hands-down the best unit in the entire game, be that missile, missile cavalry, heavy cavalry, light cavalry, or even heavy infantry. General's bodyguards are by default always among the best units in the game, because they have 0 recruitment cost, require only 200 per turn per unit in upkeep, do not require the construction of buildings to be unlocked and recruitable, never need retraining, and replenish lost casualties over time. As long as you keep the general himself alive, his bodyguards are basically an immortal unit, which is what makes them so powerful. When you add to that the fact that they are incredibly cheap - you can maintain five units of bodyguards for the same price as one unit of Hellenistic elite phalanx - and quite often are also brilliant soldiers, you have what is by default the strongest unit class in the game.
The Sarmatian Bodyguards are the strongest units out of the strongest unit class. They are rivalled for this crown only by their Parthian and Saka counterparts, but the difference between them and the Sarmatians is that the latter are not affected by the vanilla Marian Reforms. When the Romans get their hands on a huge city, as they inevitably do unless the human player takes them out very early in the campaign, the Parthian and Saka bodyguards suffer from a huge nerf - they get converted from being armoured horse-archers who double as super-heavy duty shock cavalry into being pure cataphracts, which makes them much less threatening. Just throw a couple of slingers at them, park some mid-tier or even low-tier line infantry to give cover for the slingers in case they get rushed, and the Parthian/Saka bodyguards are essentially crushed. As pure cataphracts they have a hard counter in the form of slingers. As super-heavy horse-archers, they have no viable counters at all, because they can generally wipe out a unit of slingers before the slingers can kill them thanks to their archery. While it's true that one-on-one, the late Parthian/Saka bodyguard will defeat their Sarmatian counterpart, they are overall less effective against all other units in the game after they get the Marian Reform nerf that takes away their archery ability.