Life is Strange offers few dozens of choices while playing the game. You could assume that at least few of those "important choices" will reflect in the game's finale. Unfortunately, that is not the case here. The only difference between the two available endings is a short cutscene which practically ignores everything that you encountered during the playthrough. It doesn't matter if you saved Kate, who wanted to commit suicide. It doesn't matter if you helped Alyssa to avoid accidents. It doesn't matter how you acted in regards to other characters in the game. The only thing that matters are the final minutes of the last episode during which you make your last and "the only important" choice.
The choice obviously refers to whom you want to sacrifice at the end of the game. After a series of surreal scenes made by the creators you talk to Chloe and you find out that the only choice is the choice between her and Arcadia Bay. The endings are neither "good" nor "bad" (you could even say that the best ending is the one in which you sacrifice Chloe because it has the best soundtrack during the cutscene).
Ending 1 - Sacrifice Chloe
The first ending - Sacrifice Chloe - results in sacrificing your friend in order to save Arcadia Bay from a catastrophe - a tornado. Because of the way the creators presented this ending, you might think that it is the "worse" choice, the sad one.
Ending 2 - Sacrifice Arcadia Bay
The second ending - Sacrifice Arcadia Bay - results in sacrificing the whole city with all its inhabitants just to save your best friend Chloe. The choice might seem to be the worse one because of the number of casualties and damage to the city. However, that is not the case. The creators presented it in such a way that you see yourself and Chloe leaving the destroyed Arcadia Bay in peace.