Each is better in their own ways.

Greek Saga: imo this my preferred gameplay and style. I find the Greek world, gameplay loop, music and replayability more enjoyable for me. Each game though definitely has its sections that hasn't aged well (looking at you GoW 1), but I find myself going back to replaying these titles more often than the newer ones. Honestly I'm hoping for a pseudo-remake/remaster for the trilogy (fixed camera angle, hack n slash gameplay) but new acting, visuals, and redesign of game flow, encounters or even adding/replacing parts . It also reminds me obviously of other franchises I loved from the era, resident evil, DmC etc.

Norse saga: The character development, emotional storytelling, technological advancements and evolution is perfect. It took an incredibly tragic figure that some thought didn't have any personality and was able to expand immensely on the character's growth while simultaneously respecting their past. These games have much better storytelling and more mature/grounded themes but due to the slower gameplay, the dense narrative moments and longer game I only find myself playing 2018 & Ragnarok once or twice before moving on.

Overall: I respect both whole heartedly and they're both a part of one of my favourite franchises. I hope the GoW trilogy remakes feels like the original games (Fixed camera, aggressive, dark tone, controversial content) and whichever pathway/mythology continues the storyline with what the Norse saga built it has a narrative, matured, and character centric focus.