Arn't they just opinions? I really don't know if any one of them is more correct than the other. If I'm buying a car I would rather use the one that has the lesser value and if I'm selling a car I would rather use the one that had the higher value.
Nada - plus it's more descriminating in values. But more and more I see people printing out the KBB web page and taping it to their window to justify their asking price. And I will print it out and show it to a seller if they are asking too much. So KBB is the popular choice I'd say.
But aren't those two are within a few hundred dollars anyway? At least the last half dozen times I've checked.
If you're buying, then trade-in or wholesale value is 'correct.' If you're selling, then private resale value is 'correct.'
If you look on their websites, won't they give a little info on how they arrive at their values?
When I want a ballpark number, I go to kbb.com first. There you can choose trade-in value, private or dealer retail, plus you get the average for your region, and get to pick options, and a somewhat objective condition. Depends on what you're looking for.