Same as MyLifeIsCake. Where I live, thunderstorms/heavy rain are my favorite type of weather. However, auroras are more of a breath-taking form of weather condition that I'd love to see someday as opposed to the more common and comfy feeling of rain (not floods, rain x v x").
My ACNL choice reflects that feeling, pretty much.
I love it when it snows! But next to that I would say the thunderstorms. Just because I feel like they are the rarest throughout the whole year, so I appreciate them more. And in the same vein, the cherry blossom trees are lovely too!