I always went primarily for damage on weapons and armour class on armour. Health (mainly) and mana bonuses were probably my next most desirable bonus. Early in the game Life / Mana Drain come in handy, but I found they are less required and less effective later. Passive damage skills are handy, as are sight and (to a lesser extent) hearing bonuses, but I never looked for these specifically. Stat bonuses are always good. Resistances are good, especially at the start of the game, but I don't think I ever chose one item over another due to this.
Early in the game speed bonuses are helpful, but weapon expertise will eventually drop your recuperation time to zero anyway, so later it will become irrelevant.
I avoided Frost after trying it once, and decided half way through the game not to use any charms so ignored the charm quality (except for the gold strength charm from the dragon rider Zandalor killed, that I previously used to be able to equip the bast.ard sword from the knight by Stormfist castle).
