There are huge taste differences in eggs. But it's not always the most happy chickens which lay the best eggs, or the most expensive eggs. IMO it depends on many factors like breed, diet, exercise, age and yes, maybe happiness, amongst more.
When I had chickens they ate so much green grass. Every time I went out back they were lopping the tops off the grass. Most chickens wouldn't know green grass if they saw it.
I think it depends largely on diet and stress. Stressed chickens eating only corn won't have as good of eggs. Chickens with a healthy insect and grain diet with better freedom give cool colored and more interesting eggs that I think taste a bit better. I don't really trust the factory farm making 'happy eggs', expensive and I've tried em, nothing special
/s/propaganda