Since making some petticoats and adding them under my doll dresses I must say the outfits look much prettier. The skirts stand out nicely and look just great.
Being a practical person I am a fan of the half petticoat.
Full petticoats are more difficult to fit under a dress. It is surprising how much ease disappears from the dress when you put a petticoat under it.
Full petticoats need to be made from special fabric like lawn or batiste so they are not too bulky.
The half petticoat can be swapped on and off without taking the dress off.
It can also be adjusted for length slightly just by moving it up and down the dolls body.