It obviously depends on the situation, but if I know nothing about my opponent's deck and need to negate a neutral card right now (or don't have any better options to get my hand down at the end of the turn), I tend to lean toward playing it good. Games are won by rescues, not blocks, and it activates during your upkeep, so being able to negate one of their defensive cards (making you more likely to rescue) is better than putting it on an offensive card that they may or may not need after they draw on their turn.
That said, that's a very general rule-of-thumb with as many exceptions as applications. I often try to keep my initial Woes for an in-battle negate, which means it'll be whatever alignment I need at the time, and I absolutely won't hesitate to drop it on a Moses if I need to.
