Or mood?
I know currents and energy are aprox the same "value" when you compare things in that bean-count of mathy way some people do. But the concept of "value" is more slippery than mere numbers can describe.
For example: when I'm current wealthy in the game, I feel like its very cheap to take the subway for 50c vs tp'ing for 75 energy. But is the extra time getting to and from the subway worth it? Not to mention the time spent riding the train itself.
Energy runs out if you don't remember to carry enough food or don't wish to mess around with ordering from the auction or finding a vendor. Energy takes a lot personal attention to manage. Currrents? well if you run out of currents - even at a low level in the game - nothing too terrible is going to happen to you.
The value of mood is the easiest to neglect. Has anyone figured out just how much xp they lose at various low levels of mood?