Sins of a Solar Empire: Rebellion has its hooks in me PC-wise for one very entertaining reason. Titan-class Warships, and all the shit they wreck.
Your interplanetary Empire can only have One at a time. Each of the Six titans dominates the planetary gravity well it's stationed in, as the only things of similar size are the shipyard used to construct it, and the immense Starbases used to create chokepoints along the phase transit lanes.
Here's what the TEC Loyalists (read: Defensive Isolationists) have. It's called the Ankylon.
It has 24 missile banks, 16 dual-cannon pulse laser turrets, 8 heavy cutting beam lasers, and 8 Space to Surface Nuclear missile launchers. Secondary systems include anti-fighter point-defense guns, an internal factory that build and replaces strike craft as needed, and, in general, the only thing that can stop it in battle is another Titan, or a few hundred cruisers.
In comparison, the next-largest capital vessel (in the TEC's case, the Kol Battleship), has a total of 9 Autocannon turrets, 4 beam lasers, 3 pulse lasers in a single turret, and a single space/surface nuke launcher. It is roughly one-sixth the size of the Ankylon.