Favs
van Vlaanderen-my firstreal game in CK2 with potentially one of the richest Duchies and a dynamic starting position. Plus they are the strongest Dutch family, which is pretty sweet.
de Valois-You start with Vexin and Amiens which creates a challenging starting position since you are de Jure Normandy and the King always creates the Duch of Valois and keeps it for himself.
Dulo-The only Cuman faction you can play as. I love me some Volga Bulgaria and you get to Holy War the Rus as much as you like.
de Forez-Great starting position and you get the awesome County of Lyon.
Godwin-Interesting history and Saxon England can become a very safe and stable realm if you survive the conquest.
Hate
Ludowinger- I'm not sure why but they always become Emperor. I don't now how and I don't now why, but in my last 5 games there have been long lines of Ludowinger Emperors.
Capet-The greatest Dynasty in Europe and it is always so fun to wipe them out.
Fatimid-For obvious reasons
de Normandie- I`m a big fan of the Normans and the Duchy itself, but I hate how AI Willliam ALWAYS conquers England unless you actively intervene.