For readability the second is better as you can group all these constants together at the top of the sketch. Even better is to call them const if they will never change.
Because the led variable has a global scope it will persist and you can change it from anywhere. However, in your first case it does not have a value until setup is called. In the second case the compiler initialises the memory location so it has that value when the program starts running. In the arduino this makes no difference because setup is called first. On other systems it might.