I would go for a combanation of altering heading and gaining alt as rapidly as possible. Of course in the "typical" pre-mishap sequence, it would really come down to your position when you saw the obstruction, closure rate at that time, etc. Would you have the time to avoid it within the heli's (and pilot's) capabilities.
Of course, as with anything, the issue is not to get into the situation in the first palce if one can avoid it
