I don't have a favorite, but definutely one of these:
Again - FMAB
Diver - Naruto Shippuden
Shinzou wo Sasageyo - Attack on Titan
Touch Off - Promised Neverland
Hikaru Nara - Your Li in April
All of My Hero Academia OPs
Re:Re - Erased
Primary Colors (OP2) - Dr. Stone
Kimi no Sei - Bunny Girl Senpai