for Arashi, yeah, it's probably seen a really long time where i even liked the B-sides. i wanna say the last B-side i really liked from Arashi is "How to fly" off "One Love". overall last single i liked from Arashi is "Happiness". i mean i liked "truth", "Crazy Moon ~Kimi wa Muteki~", and "Believe", but i didn't like the other songs off the single.
another instance where i completely loved the B-side over the A-side would be "Ai no Katamari" off the KinKi Kids' "Hey! Minna Genki Kai?" single. oh! and "ever free" > "vogue" for Ayu.

and i tend to like KANJANI8's B-sides over their A-sides. i like "Musekinin Hero", but "Kemuri" and "fuka fuka Love the earth" are sooo much better.