Major product for aldol condensation between acetophenone and acetaldehyde
I would expect the aldehyde to be the major electrophile in this reaction. The reason is that the steric demands for a nuelophile coming close to the carbonyl carbon are lower than for the same nucelophile coming close to a ketone.

I would expect that the enolate formed from the reaction of the methyl phenyl ketone (acetopheone) to be slightly more stable than the one formed from ethanal. This is because the enolate can be delocalised into the benzene ring. 

If we were to form the enolate from ethanal then if this was to attack the carbonyl carbon of acetophenone then we would get a tertary alcohol as the product. The major aldo product in this reaction will be a secondary alcohol formed by the action of the enolate from acetopheone on the ethanal.