The Dalai Lama thinks so - he says they can teach us more than our friends, because they set us much harder personal challenges than our friends do - here is what he says:
"Friends and Enemies:
I must emphasize again that merely thinking that compassion and reason and patience are good will not be enough to develop them. We must wait for difficulties to arise and then attempt to practice them. And who creates such opportunities? Not our friends, of course, but our enemies. They are the ones who give us the most trouble, So if we truly wish to learn, we should consider enemies to be our best teacher!
For a person who cherishes compassion and love, the practice of tolerance is essential, and for that, an enemy is indispensable. So we should feel grateful to our enemies, for it is they who can best help us develop a tranquil mind!"
This is just a simple poll but it woud be great to see a Board about the Dalai Lama and all things associated with him!
It is proposed that enemies are the best teachers