I've been checking out the amount of affection given by different gifts to the different girls and while there are definite preferences, (for example Annabelle likes theatre tickets more then other girls), it really doesn't matter at all since the most efficient coin to affection ratio is always single roses regardless of the girl. Also I believe that gift affected by mementos that boosts affection gained by happiness, but as I don't have pre and post memento numbers to check against I am basing that assumption on the fact that my one girl with that memento has higher numbers for all gifts. However that girl is Raquel who may just be affected by all gifts more to start with. The girls also have preferences for types of food/bathing items but I haven't done any actual lists, more just noticing things like Annabelle really like fish and chips compared to others.