Which is why I'm so frustrated by the need by so many of the posters to assert that their photo (and father!) is the best. The implication, of course, of the term, is that whatever you are referring to is objectively better than all others--that your Dad is better than mine, or his, or hers. The best is the objective most good--that's what the term is.
I have a fantastic father. Those of you who have been blessed to know him are aware of his kindness, brilliance, kindness, frugality, oh, and did I mention, his kindness? I could probably make a pretty convincing case that he's the best there is and get a bunch of people to agree (rumor has it my brother's already on board). But what would be the point of that? Proving that my Dad is better than your Dad? Throwing it in the faces of those who were not blessed with phenomenal fathers? Other than making people I care about sad, there is no point. No one would see that and think "gosh, I'm so glad her Dad is the best. That makes me feel so much better." The only person who might benefit is my father, and if he doesn't already know how I feel, it shows I'm far from the world's best daughter.
The same goes for spouses, friends, babies, and nearly anything else I can think of. I want all of my friends to have the most wonderful of all of those things, for them. For my friend L, A is the very best husband! For S, it's S, and for me, it's Dan. Each baby I meet of a friend is the best for them, because they were born of love and happiness and expectation. Who cares if they're cuter than some other baby? Same goes for weddings, jobs, etc. I want to be brought up, not down.
And I'm betting you do, too. So I'm going to cut way back on the word "best" and switch it up for "awesome," "fantastic," or "fabulous". Where I do use it, I'll be clear that I'm being totally subjective, talking about my own small universe. Is my Dad the best one I've ever had? You bet! He's also the worst, and the most mediocre. Ah, the joy of being the only.
I'm betting my Dad would be ok with any of those adjectives--and I'm betting yours would be, too.