I tried at on point ot make a guide to and so did TheRedMaw.

Here some notes that I told to TheRedMaw

Same Role + different abilities = different roles. Even thougth, many ships have the same role as that of ships in other factions, there special abilities, cahnge there over all role in there battle fleets. Case and point is the battleships for each pf there factions. They all do the same role, of close combat unit, nut there special abilities change how they act in a overall battle group. The TEC Kol Battleship is more of anti-capital ship, where it can work in packs to fire it rail gun after enemy shields are down, to destory enemy caps in seconds(note this only works if you have about 5 of them shoting at the same time, with the enemy's shield down). The Advent Radiance Battleship is is more of a fleet protection ship. Its abilitie to focus attack away form other ships, allows it to protect, nearly destory ally ships. On top of that, it has Energy absorptive armor, that help it, for being attacked. The Vasari Kortul Devastator is more of an anti fleet weapon. It does not have the abilitie to save ships, like the Radiance or hunt caps like the Kol, but in a fleet fight, there no one else I would not stand by, but a Kortul. The power surge increase weapons AND(trying to point it out) shields. On top of that, the increase in fire power, increase how useful disuptive strike is. This is add to the fact that the Kortual can use Volatile Nanites, that make targets easier to destory, which is supported by the power surge's increase in firepower. On top of all this, destoryed ship under volatile nanites damage other ships when destoryed.

As you can see, they are all combat ships, but there abilities, make them have very different roles in the over all fleet.

Second thing to note, is how you play the game, will effect how useful or useless some ships are to you. Half of the Vasari players will stand by the Antorak Marauder, and the other half will never build them again.