I don't think it's the uniqueness of each character. Neither is it the sounds of those familiar 26. Could it be the endless potential to make words...
Although I may be influenced by all of the above factors...
I think the biggest factor was our relationship. Yes, I actually remember meeting these letters in my early childhood days! I can't tell you about the first time that we met, because I'm not sure, but I can tell you that many of my early memories are of smiles, joy, interest, touching, making, coloring, painting, singing, and embracing my ABC's.
Of course we are still good friends. That will never change.
What are your favorite ABC memories?