How does one compare and calculate?

[Erkilmarl]

I started a new paladin game where I take leadership always when it is offered. A normal game becomes much easier that way (+ 3000 in leadership is surely much better than + 4 in intelligence, for instance).
Say, leadership 950 seems to be much better choice than attack +1. But how should I calculate? With the increased leadership I can buy 5 more Evil Beholders and get 5 x 30 attack compared to the increase of one to the attack of 60 Beholders? Or does this really matter? Or is it the increase of damage that matters?