I love WANT!, man. But I also love Be Genki, and Cha cha sing. I really only dislike some of their early singles that aren't Anata Nashi, Special Generation, Koi no Jubaku, and Nanchuu Koi wo Yatteruu YOU KNOW? I don't think I've had a problem with a Berryz A-side since....Waracchaou yo BOYFRIEND (Which I thought was contrived). So go Berryz.
I had forgotten what Aa, Yo ga Akeru sounded like, but listening to it now, I don't think it's that bad. My least favorite a-sides are Rival, Maji Bomber!!, and Be Genki. My favorite is Jiriri Kiteru, but maybe I have a soft spot for it since it was my first Berryz song.