I finally got to watch them all, this single is so much fun.
My favorite (both song and video) is "DNA", but "Megane" is close behind. I'm definitely going to listen to "Waist" the least (I don't care much for the original either, so I'm not surprised), but it's still cute and the video did a great job looking like all the weird infomercials I remember watching as a kid. I would probably sign up for Sayaaaaa's boot camp.
I had fun start to finish with "DNA", it's so easy to start singing along, and it's the one I most want the dance shot for. The "Megane" video is magic. Everyone looked great (so expressive), the manga idea was top notch. I've heard the live versions so much that the studio rec didn't quite feel full enough, but the takes they used for Rika's and Kurumi's opening lines were so satisfying. They were matched perfectly to how I've imagined they should sound in my head.
This is such a great debut overall.