The majority of people put it in the intake manifold. Sometimes putting it in the head will show a higher temp due to the exhaust heat. If you had a gauge in both places they would show different temps.
The factory put it in the head to insure that the sender was in water. Up in the intake, there's a chance it could be in an air pocket and give a false reading. Truth is, either place would be ok. There may be a difference in readings, but it's neglagable. It's in the head of some of my cars and the intake of the others. Whatever.