This is a form of Stockholm syndrome.
I've seen this happen before. It's okay to like something more than somebody else. Nobody needs to die here!
DG had some good characters like Rikki and Addison but also has its share of cartoonishly exaggerated archetypes. The lack of characters, apart from the protagonist, in Horizon worked for me because you were on a long journey across lands and mostly on your own. You were rarely forming attachments, just meeting people and moving on quickly.
DG was retreading the well-trodden path of zombie apocalypse whereas Horizon has robot dinosaurs seemingly having exterminated man. It was genuinely new and finding out why was a huge part of the appeal.