preface: lets open the mighty gates to the cosmos and mythology. Consider the great list of all the religions that have existed, think of all the stories that have been told throughout the aeons, spanning all cultures... really give this one some thought.
who do you choose?
lets break it down a bit: the general options you've got are:
Cosmos Gods (sun, moon, sky, day, night, creator...)
Chthonic Gods ( earth, water, weather, underworld...)
Human-sphere Gods (War, justice, peace, love...)
I'll allow demi-gods too, but you've got to admit your imagination could use some work...
some references for you:
be creative, link interesting myths and stories associated with your choice, and if you're going to call out another person's god, you better have a rational argument for why your choice clearly dominates.