Hmm, I guess I like the arrangement and the concept, and I've been listening to the song a lot lately too. I like how in the PV it's like they're just performing in a high school talent show and overall it shows the girls as being down-to-earth. I don't like those pop videos where the artists are just elevated to the max as gods or something, and then the song turns out to be crappy, lol. A lot of AKB48's videos are fun to watch.
I like their happy-sounding songs more than the "mature" ones, even though I did like both RIVER and Beginner when they came out. I liked Namida Surprise a bit more a few years ago too, but it's too energetic to listen to while working on something because it's kind of distracting.
The top 5 on my list could kinda switch positions around, really. I think Everyday, Kachuusha can easily move up to the top right now.