Torpedoes have the better chance of sinking the ship, but if you can coordinate the attack (wishful-thinking), get there all at once (best case scenario). Fighters engage fighters, and the bombers do their thing.
I've heard (correct me if I'm wrong) the best attack position for torpedo planes is as you say "split", from both port & starboard bow. The least anti-aircraft fire.
Nowhere to run, nowhere to hide. Avoiding (combing) one puts you broadside to the other, and staying true gets you done by both.
Dive bombers can make a mess out of top side (un-turreted positions), and near misses can cause (in some cases) severe hull damage (like mines), which may very well take the ship out of the fight.
Having all (either one) the same simplifies (to some extent) the defense.

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Morbius, Morbius! Something is approaching from the Southwest. It is now quite close.