Properly used, all ships own.
Thinking it over more, I'd say the further you get in the game, the less useful defense gets for smaller ships.
For example, early game. You manage to fit 1 of each of the +1 defenses on a fighter, and add in a couple Laser Vs. So you're at 2 Damage, 3 Defense, 9 HP. Your opponent maanges to fit 5 Laser Vs. 5 Damage, 0 Defense, 9 HP.
Odds are pretty good that the ship with Defense will win- just because the Defense will stop most incoming attacks. Meanwhile the 5 Damage ship will likely take damage every time.
Now let's scale that up to the other end of the spectrum. I have a pair of Black Hole Eruptors, you have two Aereon Missile Defenses. That's 50 vs 40. Still on the tiny hulls. The amount of damage that's likely to get through is going to rip apart the defensive ship.
If you have 9 HP and 2 damage gets through, you'll survive. If you have 9 HP and 10 damage gets through, you're toast.
Thus, as the weaponry moves up the scale, it becomes less and less feasible to bother with defenses on your smaller ship classes. Meanwhile your capital ships are going to still get the full benefit- because 10 damage against 150 HP is a cut, not an evisceration.
In the late game I'd guess that the old saying about the best defense is a good offense does come into play (regardless of what certain robots tell you), because the only way that the smaller classes of ships will have an effect is hitting fast and hard, before their target can strike back.
Course, big enough ships will strike back regardless. And then it's no fun to be a fighter pilot anymore...