Personally I find it much more impressive when someone builds something big and complex in survival mode. He has gathered all the stuff by himself, he has had to think about how to get it done when you can not just fly around and put blocks where you want and most of all he has put a lot of time into it.
Imho for something to be as impressive in creative mode it needs to be something really personal, difficult and complex. Something that has taken equal amounts of time as the smaller structures in survival mode.