As per recent interview, Cryptic doesn't sell many cruisers in their store. I would suggest that this is because few of them bring anything really unique or high performance to the table.
How about a Torpedo Destroyer. A ship with reasonable agility (turn rate 9-10), and cruiser style hull and shields. Has only 3/3 standard weapons, but has a 7th weapon slot which can ONLY accept torpedo weapons. A torpedo mounted to this slot has 360 degree targeting. Comes with a unique console that causes your next special torpedo attack to double. Once you trigger the console, you have 30 seconds to use High Yield or Spread and then fire. When you do you get two HY or Spread attacks back to back. 1:30 cooldown? Officer layout should prioritize engineering and then tactical, so possibly XXXX / XX / XXX / X / XX
Such a thing would be... interesting! Different.
So what would you buy? Try to be... vaguely reasonable.