It was always Daddy; although some times my dad would sign his cards as "Dad"..
As he grew older, he changed it to Daddy.
This sounds weird; but as my mom, became more deaf and began into her early dementia, it was easier to get her attention my Saying: "Yoo-Hooo!"... She knew it was her. I did always refer to her as Mommy.
Mom and Dad. I may have said Mommy and Daddy when I was very young, but I can never remember an instance where I used those terms. I called my step-parents by their first names, save for a spell when my dad first got married where my he had us call my stepmom "Miss *name*" for whatever reason (he can be an odd bird sometimes! I think it was a respect thing? I didn't call him Mr. Dad...lol!)
My husband claims he has only ever used Mom and Dad as well, but whenever he gets a card or whatever from his mother, she always signs it "Mama." He swears up and down he never called her that.
For the longest time my mother was Mamacita. I have no idea why. My father was in the merchant marines, so he was always gone, mostly for months at a time, so I never really knew him. My mother spoke of him as Daddy to me, so that's what I called him.
Our adult daughter refers to her father as Daddy, but she really doesn't care for me, so she calls me Jackie. To our granddaughter we were Gran and Granddad.