Death Note, Ookami to Koushinryou Recommendations
Spice and Wolf is the Death Note of romance anime. You have a similar plotting protagonist - not one who's out to rule the world, but rather the marketplace. If you enjoyed the "out-thinking my opponents" and "conceiving and executing a plan in the face of adversity" of Death Note, Spice and Wolf will give you more of the same.
In addition, both have supernatural companions who have enhanced senses that help them in their plotting. Light, however, isn't in love with Ryuk =p
Both feature a god dropping from the sky and forming a partnership with a mortal young man and both main characters use their wits and intelligence to overcome any obstacle.
The only thing similar about these anime, and the reason i loved them both, is because they cause you to think about certain events rather than just mindlessly watching it.
These 2 require a whole lotta thinking in order to understand what the hell the characters are talking about. Also, both of them have 2 story arcs that make up the entirety of the anime. Some fast-paced and climactic moments are included as well.