What theoretically workable weapons (they don't necessarily have to exist, they just have to be possible with a little bit of unobtainium) would be the most effective for ship-to-ship combat in space?
The technology level in my universe is roughly Stargate / Honorverse level. Here's what this means:
Energy shields exist, but they aren't Star Trek-level perfect. They work by absorbing all the energy of anything that hits them from the outside, storing it in capacitors. Once the capacitors are full, the shield goes down until the capacitors can be emptied. The capacitors can be used to power the ship's systems, but don't have an especially high capacity. As a result, offensive tactics in my universe center around hitting your opponents with large salvos. Also, it's worth noting that they aren't very effective against missiles.
- EDIT: While the shields aren't infinitely powerful, they do have quite a bit of durability. After all, they have to protect the ship against interstellar gas and micrometeorites while the ships are moving.
Anti-missile countermeasures are effective, but not 100% effective. For purposes of this question, let's set the optimum effectiveness at 98%, with a small decrease in effectiveness as the amount of incoming missiles increases.
Power supply isn't a problem. For purposes of this question, they have something along the lines of a ZPM.
Most ships have some ablative armor and anti-rad measures. As a result, while missiles do a lot of damage, a single missile / torpedo getting through isn't the end of the world.
EDIT: "With a little bit of unobtainium" means "slightly better material sciences", not "do whatever the heck you want". In other words, answers must at least be theoretically plausible. For example: directed energy weapons and (small) antimatter warheads are okay, but de-mat guns aren't.