I would say the top one because her gravid patch/spot(dark area at the back of her tummy) looks bigger/darker than in the second one- although it is hard to tell from the pics as im not very good at that kind of thing unless i see the fish in life.
The gravid spot is caused by the frys eyes which can be seen as it is quite a see-through area of the fish's tummy; the eyes darken as the fry develop making it look bigger/darker as the fish's pregnancy develops.
I would say the second guppys tummy looks bigger but because of the gravid spot i would say she is just expecting a larger batch of fry than the first guppys.