I don't have just one favorite. With my adults, my Light Brahma and my mixed hen are my current faves... but I also really like my Australorp. My favorite from my old flock was my OEGB. Sweet little hen and a great mama.
With my chicks, my BO and RIR pullets are the sweetest and my Ameracauna cockeral is the funniest (even if he currently looks like his namesake, Buckbeak from Harry Potter).
My favorites are my Silver Duckwing OEGB, and my Red Pyle OEGB. The Red Pyles were the first official pair I bought, and the Silver Duckwings were all given to me.
Doesn't count as a favorite because I don't own any, but I really, really want Salmon Faverolles, Standard or Bantam.
The longer I have silkies, the more I like them! Who knew? When I first got mine (June of last year) I wasn't going to keep them, I hated them and wanted nothing to do with them. But they kind of grow on you after a while
Second would probably be my d'uccles, but second place is held by many of my breeds!