The Winter 2015 wave was in my opinion the best wave of Bionicle we ever got, I love all the sets and I don't hate any of them.
Summer 2015 was Ok, I think there were some under-rated sets, like Skull Slicer, but there is only one I can truly say is terrible, Skull Scorpio.
Winter 2016 was good, not great. It had a few bad sets, like Pohatu and Ketar, and some ok sets, like Lewa and Kopaka, but there were still great sets, like UTH, Onua, and Tahu
Summer 2016 was ok at best, the beasts were fine, if you pose them right, UTD is good, and Ekimu is great to me.
Also Gali 2015 is my favorite Toa set of all time, she is just Fantastic.