Favorites

[Mariska Greenleaf]

Well, as the oldest of four children, I'm sure that every parent has a favourite, which doesn't involve that he/she doesn't love the others of course...
I've always been the favourite of my mum, because I was her first child, and therefor I'll always be very special to her.

Maybe Tolkien himself had a favourite among his children, maybe that's why he used the situation in his work. And I assume as you say, Eomer, that maybe in the elder days having favourites was quite a common thing.
And maybe even today in some cultures, it's common that boys are more wanted than girls...

The Denethor case is particularly interesting because he favoured Boromir over Faramir, even though (and probably because) Boromir was less like Denethor.

I think Denethor liked Boromir better because he was his oldest son. If you compare Boromir and Faramir individually to their father, I think that Boromir is more like Denethor than Faramir is.