[Matrixbeast]

We may not be the biggest fandom around, but I say there's enough of us for Bandai (And now Hasbro) to create multiple collector oriented lines.

Anyway, my decisions were based on general observations.
Goseiger has it's merits (I freaking love Gosei Knight), but most are overly indifferent to it, and find it's constant villain swapping tedious as it basically resets the status quo every 14 episodes. While optimistic heroes are fine, most people found the Goseigers to be optimistic to the point of obliviousness, and their air headed antics and decisions were eye rolling.

Kiva suffered from being too melodramatic and just not being able to handle the shifting tones. Most people found the 80's timeline to either be the best part, or found it too ridiculous. Wataru was seen as just too uninteresting a protagonist until the final 3rd of the show, while Nago seemed to go from straight laced to comedically obsessed and straight forward, which kind of lowered his character in the eyes of some. Kiva's only universal praise is it's designs (Which are pretty on point)

Most "Bad" Sentai and Rider series people are pretty 50/50 on. For everyone who hated Faiz's lack of communication, you have someone who found it genuinely enjoyable and loved the characters. While some people may find Boukenger bland and dull, you have others who loved the adventure aspect.
I'm just using general observation, and it seems Goseiger and Kiva have the largest "Bad rap" compared to other shows.