Geek vs. Nerd
Great question! I love it.
"Geek" is honorable, whereas "nerd" implies dippy to me.
I especially like the phrase "to geek out on something." It suggests you are aware your appreciation of the thing is a little frivolous, but you can't help getting your hands deep into it.
A generation or two ago, the word was "jerk," which kind of meant "loser nerd." Then there was that song "Cool Jerks," which sort of tried to reclaim the jerk term in the same way that "geek" has been reclaimed.