I apologize in advance if any of these aren't unpopular. I haven't been involved in the Bionicle community for many years.
Just because the G2 Toa have more articulation and were more poseable than G1 Toa doesn't automatically make them better.
Umbra's color scheme of Metru Green and Keetongu orange was actually pretty good. It was the silver that ruined him.
The designer of Hewkii Mahri's mask did nothing wrong. However, the same can't be said for whomever decided on his color scheme.
I'd go as far to say that the villains of the Stars wave were somewhat "good". Their Av-Matoran design was obviously pretty bad, but at least they were somewhat unique. While the Skrall wasn't exactly anyone to write home about, getting a different version is somewhat nice. We had also never gotten a proper Heat Vision Rahkshi and a bad Rahkshi is still a Rahkshi, which is pretty neat. And Nektann was a new character with a backstory, which I personally prefer greatly over a dumbed down version of an already existing Skadi, which is what we got with all three heroes. It's actually almost impressive (in a horrifying way) how Lego designers were able to simplify Gresh's already simple design even further for the Stars.