Taking into account poor audio quality, etc., I'm not feeling either song too much. At least the DIY♡ song has a beat and is more energetic, so I'd choose that one if I had to (I will admit some bias, though; I don't follow S/mileage and Riho seems to be EVERYWHERE lately, so I'm a little burnt out on her).
What I would like, though, is if this means more subgroups in the future. What I would really like is if they did it like the original subgroups -- i.e. Nacchi was the center of MoMusu, so Tanpopo and Pucchi Moni were created to spotlight the other girls.
Failing that, give me a Momo's Pink Rangers subgroup RIGHT NOW, Tsunku. I don't even care how they would sound.