So simplest part first:
All IJN CVs have AP bombs except Kaga, which has HE bombs. USN HE bombs deliver decently high, consistent damage. AP bombs have the potential to citadel, and can delivery large blows if this happens - however, this requires a great amount of precision, a decent amount of luck, and some ships just have armor such that you can't do it.
Now for torps, mostly their T10 characteristics but some apply to all tiers:
USN - highest alpha strike/salvo damage, worst aiming, slow torps
IJN - middle aiming, fast torps, middling damage
RN - extremely short range torps and they're slow, but they have the best aiming. If you know what you're doing, and then approach parallel to a ship, then turn in while aiming to still get a perpendicular drop.
In terms of aiming, RN are my favorite. They can pull off silly drops that no other nation can do. But the IJN fast torps are nice because they're easier to lead, and the USN torps are nice for blapping big slow targets for a large amount of damage.
Kaga is an exception to much of the above. In general, premiums may be an exception to any particular point. It's worth noting that 2 Shoukaku torpedoes do more damage than 3 Kaga torpedoes.