Hard to say now, but AIWFCIY will be a bigger classic in the long run. IWALY is more iconic, it's by far THE signature song of one of the most successful, famous legends in music history, and was one of the most successful singles ever, simply massive at it's peak... Yet, once the iconic-ness of it fades and those of us who remember her huge peak die and/or become less relevant to the musical landscape compared to the newer generations (much like I'm pretty sure AIWFCIY would be landsliding an Elvis song or something), the song that stays more current/relevant will be the bigger classic. I can't guarantee AIWFCIY will keep charting every year decades from now, but it's doing a lot better in that regard than IWALY*
* And it should go without saying, but that's not a knock on IWALY - more a compliment to AIWFCIY, which is very atypical in the way it surges every year, even for a holiday song.
