Spain, for the infantas (Elena and Cristina) and their children, I also like Letizia, but I find her less interesting lately, since the plastic surgery on her nose. I also think this is the hardest-working royal family.
Denmark, not so much for the family members (although I don't dislike Mary nearly as much as I used to, I'm more neutral now) but for the traditional style of the monarchy, hats, etc., and for Denmark itself, which I think has a magical quality.
Belgium, I like the Crown Prince couple, beautiful kids.