The Scout is probably one of the most important, yet under-appreciated, ships in the game. The Scout carries a very small compliment of armor and weapons, but it's speed and accelleration are top notch. Probes are also a vital element of any defense. Without a network of probes to tell the commander what is going on, who knows when that Cruiser is going to hop into your sector. The Fighter is the all-purpose spacecraft of the Allegiance world.
Fighters are fast, and have decent anti-ship weaponry.
The Interceptor is the ultimate dogfighting craft. With it's ability to use its thrusters in any direction at full power, as well as its standard weapon the Minigun, the Interceptor can deal out huge amounts of damage to any fighter-class craft. They also can equip EMP cannons which cause major shield damage, but deal 0 hull damage once a ship's shields are down. Int also equip Light Boosters, which make them very effective in long distance chases. However, they are unable to ripcord and their standard top speed isn't that fast, so be prepared for a long trip home if you run out of fuel for your booster.