I agree that it's all purely subjective. It comes down to arguments like this:
PERSON ONE: I really love The Tempest, by William Shakespeare. It's just so imaginative and the characters are amazing.
PERSON TWO: Nah, I prefer Eclipse, the third book of Stephenie Meyer's Twilight saga. I mean, it has vampires!
PERSON ONE: But The Tempest has got wizards - and magic too!
PERSON TWO: I prefer vampires...
The fact that their emotional opinions basically mean the same thing ("I like this, but not this") means they cancel each other out. It's impossible to say which is REALLY better: "The Tempest" or "Eclipse".