Fighters: Fighters are cheap ships which in great masses can soak up huge amounts of damage that would kill capital ships, which makes them valuable in saving money. Having more fighters then your opponent is nothing less then imperative due to later outlined combat strategy. Fighters use laser tech, and it is recommended you have no less then 22 levels of this tech for effectiveness. The added 20% firepower over an opponent with 18 laser tech is astounding. They kill Fighters, Bombers, Heavy Bombers, Corvettes, Destroyers, Frigates, Ion Bombers, Ion Frigates. They are slaughtered by heavy cruisers or larger ships.
Bombers: Bombers are twice as expensive as fighters yet do not return double the fighter stats. Armor is not increased. Bombers are useful in some amount (a few thousand per armada is recommended) due to their ability to assist against Cruisers masses, which are extraordinarily powerful in combat. They are not worth large swarms, however. 20 Missile tech is advised. They are the second best ship for cheap damage absorption, so having at least some is a fantastic idea. They kill Fighters, Bombers, Heavy Bombers, Corvettes, Destroyers, Frigates, Ion Bombers, Ion Frigates, Cruisers, Carriers. They are slaughters by fighters and battleships or larger ships.
Corvette: Corvettes are nothing but tough meat shield with sufficient attack (8.4 at laser 22) to assist in attack enemy destroyers, and if they are idiotic enough, frigates. They also assist in absorbing larger blows. They kill Recyclers, Cruisers. They are slaughtered by fighters and battleships or larger ships.
Heavy Bombers: Heavy Bombers are critical pulverizers of the middle tier (Cruisers, Heavy Cruisers) and at least 700 is recommended. They are ineffective against battleships (at 14 plasma, vs 14 shielding, 128 Heavy Bombers will kill 1 Battleship and do .02 damage to another) and are effective against low shield Cruisers-HC. They are slaughtered by fighters and battleships or larger ships.
Ion Bombers: Don't make these, unless you’re a snork.
Destroyers: Destroyers are a plasma ship that are tough piercers into HC and Cruisers. Being quite cost effective (Plasma 18 recommended), they form a valuable punch into an opponent's upper-middle tier. The Upper Middle Tier is the section of a fleet which wins a battle, and destroyers can turn the tide. Destroyers kill crusiers and heavy cruisers. They are slaughtered by fighters and battleships or larger ships.
Frigates: If you are retarded, make your fleet nothing but Frigates and Ion Bombers.
Ion Frigates: See “Frigate.” If you really want to argue about the worthlessness of Frigates, Ion Frigates or Ion Bombers, Brainy will gladly devastate you with the math behind why they are the largest waste of your credits possible and send you home crying like a little girl. Do you really want that? No, you don't, so just don't build them please.
Cruisers: One word for this; lots. Cruisers will devastate an opponent’s Heavy Cruisers with ease as well as forming meat while destroying battleships. A decent fleet should have no less then 2000 cruisers in it. Cruisers, at Plasma 18, pierce half an HC's armor. Two cruisers can kill an HC for 400 credits while an HC costs 500. Cost effectiveness at its finest. They kill everything from Heavy Cruisers to Dreadnoughts. They are slaughtered by large amounts of fighters, bombers, heavy bombers, destroyers or Titans or larger ships.
Heavy Cruisers: Heavy Cruisers are the ships that win large battles. Being able to smash in battleships without a problem as well as being able to mow down Bombers and other low tier ships, they are the decisive element in a battle. Paired with large cruiser masses and fighter swarms, the battle is certainly yours. 400 are recommended if you have 2000 cruisers. HC are extremely vulnerable to Heavy Bombers, so it is recommended in steps below to eradicate those. Heavy cruisers kill fighters, bombers, battleships through titans. They are slaughtered by Heavy Bombers, destroyers, cruisers and Leviathans.
Battleships: Battleships are a highly overrated ship good for little other then punching destroyers and lower and pummeling Dreadnoughts and above. About 50 or so is recommended in an armada to assist in hitting bigger ships. 100 if there are many enemy titans. They kill fighters, bombers, corvettes, destroyers and Dreadnoughts, Titans, Leviathans and Death Stars. They are slaughtered by cruisers and heavy cruisers.
Dreadnoughts: DNs are a tough ship that will hit anything below Cruisers hard. Good against weak composition fleets.
Titans: Titans are superb against the entire middle tier (cruisers) and below, yet BBs and DNs will utterly destroy them. Two or three max is fine.
Leviathans & Death Stars: Don't worry about building these until you have at least 5k cruisers and accompanying fleet for a leviathan, 10k for a death star.