The Greek Hoplites, when used right, can become one of the strongest melee units of the early game. You should always move them in formation to make use of their special ability. This will give them such a big boost in CS that they'll face down any melee army comprised of Ancient Era units.
Note that without the bonus strength, a Hoplite is just a normal Spearman! And this will make him weaker versus melee units, such as the Warrior.
Civilopedia entry Edit
Give a bunch of citizen-soldiers ten-foot iron-headed spears (called doru), put them in a tight formation shoulder-to-shoulder, and the hoplite phalanx appears. In the 8th or 7th century BC, the Greek city-states first began to raise hoplite units – composed of those “free” citizens who could afford the bronze armor and the doru – for fighting among themselves. As the Persians found out, hoplite phalanxes were pretty effective against others as well. Although enemy archers might pick off a few (most of the arrows of the time were too light to penetrate the bronzewear of the Greeks), a phalanx of hoplites could generally sweep everything from the field in front of them; the greatest threat came from exposing their flanks, or losing formation moving over rough ground. The hoplite-phalanx survived for almost 400 years, through the age of Alexander the Great still dominant, until it came up against the Roman legion, faster afoot, more flexible in formation, and more adept with their short swords once they slipped past those unwieldy spears.