I find pretty much all fantastical worldbuilding (including mythology) interesting, but Norse is my favorite mythology too. If you count modern fantasies that aren't meant to explain the real world, Brandon Sanderson's cosmere is my favorite.

Christianity -- probably because that's what held me captive for so long. When the Greek storytellers wrote the NT, they were probably laughing their asses off at some of the bullshit they were required to include. They really were the masters of story telling.

Greek Mythology. The story of Hades and Persephone.

I also like the Norse mythology. Odin was my favorite "god" when I learned about that way back in those junior high school days.

The Hindu mythologies (in general)

I'm from the northern part of Norway. Nordland , we grew up with these sagas, not as a mythology or religion but as stories and faded history. Trolls became the surrounding mountains and Odin walked the shores disguised as a old man. I'm not religious but the Asa belief runs thick in my blood.
Visit Lofoten island if ever you'd like to submerge yourself in the Norse mythology.

Catholicism/Christianity

Okay, I know this is not technically mythology, rather, fantasy, but it might as well be. I am thoroughly smitten with Tolkein's Middle Eath saga. So much rich symbolism and morality analogies, it's great!

Greek the one we were taught in School.

Comparative Mythology, in the Joseph Campbell vein, but my favorite individual mythology is Christian Mythology, probably because it's the one I'm most familiar with. It's near impossible for a rational person to see the value in it as long as they insist on reading it as literal. A metaphorical reading need not conflict with science in any way.