My opinion: The Rebel cruiser is a great ship, even greater if you get an RCS Upgrade, a thrust enhancement, and engine upgrade (which I strongly recommend). It has plenty of shields to hold its own in combat and selling the Rocket Launcher will add even more weapon space. I recommend doing so, as well as purchasing two mass expansions. Then equip your Rebel Cruiser with a layer of each kind of armor, five proton cannons, two laser cannons, four proton turrets, and plenty of missles — your Cruiser will be the best fighting machine out there. Space bombs are also an option with this ship, since it has the room to buy them.
Computer controled: The computer tends to have the Cruiser stand still (because of its slow turning rate and acceleration) and launch its fighters at you, as well as missles. Close combat is difficult because of the three proton turrets but a well equipped Kestrel should be a able to destroy a Rebel Cruiser without too much difficulty.