To be fair to humans, there are probably more common items that boost base damage than their are boosting percent damage, particularly if you are going purist. Fine sword, Skullpicker, spoons in some dungeons etc. And extra total damage for fighting the boss is arguably more useful, particularly if you have
prepped anything to help with the initial leveling.
Also, orcs are ugly, and who wants to look at an ugly sprite when you could be looking at a sexy human?
Items that boost base attack:
Spoon (+1) (s)
Hero's Helm (+2)
Fine Sword (+4)
Skullpicker (+5) (note: Taurog's boons also grant attack bonus)
Trisword (+2 - +7)
Items that boost attack bonus:
Perseverance Badge (+10%) (s)
Badge of Honour (+10%)
Dwarven Gauntlets (+20%)
If we count sub-dungeon specific items:
Yang's Sword (+3 base attack)
Blade of Yin (+3 base attack)
Penance (+2 base attack)
Bound Sword (+15% attack bonus)
However, all that must be taken in the context of there being a preparation to give you two extra attack boosters, and extra attack bonus is a common class feature while extra base attack is very uncommon. In fact, Dracul and Taurog are the only deities that actually offer base attack at all (and even then not much).