Well, my favourite couple is Willem-Alexander and Maxima! (What a big surprise... )
Other favourites are (in random order):
Filip and Mathilde, Beatrix and Claus, Albert and Paola, Charles and Camilla, Felipe and Letizia, Maurits and Marilene.
Prince Naruhito-Masako
Charles-Camila
I put them on the top because they have shown their relationship very strong specialy with the problem they have faced.
For me these couples bellow seem to have a genuine love each other.
Willem Alexander-Maxima
Philippe-Mathilde
Haakon-MetteMarit
1. King Carl Gustav and Queen Silvia of Sweden
2. Crownprince Haakon and Crownprincess Mette-Marit of Norway
3. (the late)King Hussein and (former)Queen Noor
4. King Albert and Queen Paola of Belgium (after the scandalous years...)
5. Queen Beatrix and Prince Claus
6. Princess Margriet and Pieter van Vollenhoven
7. Grand duke Henri and Grand duchess Maria Teresa of Luxembourg