For a Druid there is no real reason to favor +attack power over +strength. Unless +attack power gives a lot more. Especially not if you have the talent Heart of the Wild, which most feral druids do.
With the talent it looks something like this:
1 strength = 1.2 strength (Cat form) = 2.4 attack power (Cat form).
For instance, 40 strength would give 48 strength in Cat form. That's a bonus of 8 strength, or 16 attack power. Which means that to outweigh strength you would have to get 16 attack power more than usual.
Same goes for agility. You only gain 1 attack power per point of agility, but it also adds do your dodge rating, your armor rating and your crit rating. Plus, when in Cat form, you gain attack power equal to a percentage of your total agility.
You can check out my equipment
here. I have around 1500 attack power in Cat form and it can only go up.
While getting raw attack power might seem more efficient, you must remember that agility gives a pretty decent chunk of crit rating as well, not to mention 2 armor points for every agility. And if you have Heart of the Wild, getting strength and agility armor sets (of the Tiger, of the Beast, of the Grove) over pure agility and attack power (of the Bandit) or pure attack power (of Power) is very much worth it.
Edited, Apr 30th 2007 11:40am by Mazra