I quite like seifuku no mannequin and shakiism but not many of their songs has that wow factor for me
They don't have the big song yet, like AKB's River. It's expected since they are kinda new. I think the quality of the songs are improving. Girl's Rule is so much better than Oide Shampoo IMO.
I haven't listened to all B side yet, so far my most fave is Seifuku no Mannequin
One of my favs. I think my most fav right now is Kimi no Na wa Kibou. I find it really touching.