Well, actually the Bernouilli effect has its part, and so has the Coanda effect; however most of these explanation concentrate on an artificial setup, without taking in to account the actual angle that the wing makes with the air stream. When you learn to fly, you're first told that the angle of attack is the most important parameter to get lift. See the wikipedia page : http://en.wikipedia.org/wiki/Angle_of_attack

The Bernouilli and Coanda effects, in most flight configurations are of relatively minor importance, except on some particular aircrafts.