Well, really this is a question of area and volume. How big is a big cake, and how big is a small cake? Obviously if they have the same volume then the small cakes combined will have more frosting, because they have more surface area. But if you enjoy the cake more than the frosting, you might go with the big cake. It actually depends on what type of cake it is, too. If it's potato frosting or something, then yechhh, take the big cake so you can scoop that gook off. But what if it's something yummy, like PRETTY MUCH EVERY TYPE OF FROSTING!
I'll take 30 tiny cakes.
Would you rather ride a pterodactyl or a giant eagle?