Are bombers the ultimate weapon?

Winning with carriers is certainly one option. i agree that for much of the game, you do steamroll everyone. I'm surprised you have luck with missle bombers though, plasmas always work way better for me. The major downside I see with a fighter-heavy approach is that carriers tend to be relatively weak hull-wise,which means that if a fleet of alien capital ships jumps right on top of you (which they have a habit of doing), you're toast. This has happened to me more times than I care to recount.

I've actually found that my most successful games/highest scores are those where I focus on my onboard weapons and use repair/shield drones exclusively. Once you get 3+ death rays, it really doesn't matter what else you have.