It’s not about “trying to figure out which of two good games is objectively the “best”,” but more like Horizon Zero Dawn coming out right after Breath of the Wild. Horizon is a truly great game, but it suffered from coming out right after what turned out to be a definitive open-world game. It’s not about better, it’s about timing. People would have had different expectations of Starfield had it come out before BG3, just because BG3 changed some people’s expectations of things like quests and ways to do them.
And again, I’m just going by what I’ve seen in reviews and something I’ve noticed in them. I’m never going to play Starfield (nothing against it, but I physically can’t play first person games), so I can’t say one way or the other about what the quests and worlds are like.