I don't claim to be an expert by any means but from my understanding, I would say one drift, with a long gradual taper, think triangle profile with rounded corners. The eye should be a taper that matches the wedge that the head requires, which comes down to intended use ie a axe for hardwoods, softwoods or splitting or if you want a general purpose. Eye size will depend on overall weight also heftier head would want a slightly wider eye to handle the increased force. Try all the axes you can and see which you like and which you don't , what patterns you like then match the eye according to shape desired.