Oooooohhh! A fun game!!
My "dream horse" would be by the Hanoverian stallion "Dancier"
(By De Niro by Donnerhall and out of a Lauries Crusador xx line)
And then out of a mare with one or all of the following lines:
Rubenstein (or son Rotspon :P)
Quattro B (or sons Quando-quando, Quarterman or Quarterback)
Cor de la Bryere (or sons Come Back II or Calecto V)
Basically I love the Donnerhall line - it is the most highly represented Hanoverian line in the Olympic dressage ring. However I do think he needs some refining and I like a little heat - hence the Lauries Crusador xx lines on the bottom of the stud's lines.
However I do need a shorter horse and for sure the Rubenstein lines generally throw a shorter horse - Come Back and Cor de la Breyere lines can throw tall horses however they are usually still small in the body with a long leg and a notably active hind limb. Quattro B is a line I have never personally ridden however it is a highly ranked line in Europe, has a French flavour and seems to throw a lot of nice moving, willing, international quality horses. I would love to try one!
A combination of my 4 favorite lines would be totally ideal!! My horse now has 2 of them - by Rotspon and out of a Come Back II mare.