Without actually seeing the dress you are planning on wearing it is difficult to offer an opinion. There are so many factors to consider - such as the shade of pink, whether the dress has a belt or sash (this would impact on any accessories that the shoes have and may end up detracting from the overall look) and the general cut of the cloth.
Do you plan on carrying a clutch bag or wearing any hair adornment as these would certainly influence my decision. I also noticed that No4 has a slight open toe, so you may need to buy a nail polish that compliments the shoes or dress (although it is more natural to chose a colour that would go better with the dress than the shoes as it would just get lost otherwise)
So having factored in all the above, and taking into consideration the information provided by yourself I would say the answer is obvious.
Number 2 - because they are cheaper