I like the contrast between the villain and the hero in this season.
Saitama is all powerful and can kill anything in one punch. He is so bored of life, and his emotions are dulled, he can't feel anything or get excited anymore.
Garou is a powerful man, but he is not all powerful. He gets beaten up half to death when he fights against S-rank heroes, but he frigging loves it. He proclaims that he is happy about the learning experience, and he is happy that he still has room to grow. He has so much drive and passion.
Garou is basically what Saitama wants to be