Ah, you touched on something else that can't be over rated, and that's the mental part. Pocket presence, ability to read a defense, and make quick and proper decisions. Accuracy is huge, no doubt, but it won't mean much if the QB doesn't have the mental presence required for the job. Nore will having the mental attrributes for the position, but no accuracy (see Fitzgerald).
Not to bring an old debate, but Flutie often stated how important the decision making ability is. He ranked it number 1.