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Hmm, perhaps the most accurate statement would be that they are equal. This is because different tactics are chosen in different situations. I voted for defense, and now I will explain why. Warrior heroes (Knights, Haven, Orcs, etc.) mainly rely on their army, i.e., they develop both defense and attack. Magic heroes (Necropolis, Academy, etc.) usually don't allow themselves to develop both defense and attack simultaneously because their place is usually taken by magical skills. And here the question arises - what to choose, defense or attack? And here, in my opinion, it is better to choose defense (except for the Warlock and the Dwarf, who can choose both defense and attack) because the hero's army must withstand the attack while the hero casts spells. So, defense has a slight advantage in terms of prevalence, so to speak.