stove burner size vs efficiency I'm curious if there's a best choice for what burner to use (mostly for electric bill, but I'd be curious about any other unforeseen consequences), given that I have 2 options of burner sizes, and my pot of water is big enough for either one.

Of course if the pot is smaller than the burner, any "excess" burner size (any of the heating element touching air instead of the pot) results in waste (I would guess very close to 100%). But when the pot is large enough that the hearing element will reach out in both cases, that shouldn't be an issue.

This question and its answers note that the wattage of a small burner is lower, and it produces less heat. So to get a pot of water boiling (in a similar amount of time), I would set the smaller burner to a higher setting. Does that end up using the same amount of electricity?
I would cook on the largest burner available that is not too big for the pan or pot. The smaller the burner is the longer it will take to bring to temp and the more wasted energy you'll have from radiation from the pot and evaporation. I would also set the burner to its highest setting to bring to boil and then turn it down unless you are maintaining a boil in your recipe.