Whatever the picture dictates. To me shadow detail can be downright distracting sometimes, and am no stranger to both completely black shadows, or areas of highlights without detail. Under-/over-exposed and/or under-/over-developed - technical terms defined by technical standards usually - while creating a successful print might break all the rules in the book. I've come to a point where I only look at a print and decide whether it moves me or not. That's all that really matters to me.
But, I think that it's best to leave options open, so I usually attempt to insure I have enough shadow information and avoid blocked up highlights in the negatives. It makes things easier come printing time, and I use printing technique to 'hide' content. It's much easier to 'hide' details that are present in a negative, than to try to reveal something that isn't there.
What I think is utterly important is to look at our own work flows, and try our way with things. If we're not sure how we like our prints, maybe it's a good idea to find a familiar scene and bracket exposures and/or experiment with developing times and agitation. Just so that we can find a negative that prints exactly how we like, and just forget about conventional wisdom for a while.