Zero-One is the series following Zi-O so if you want to watch the Kamen Rider seasons in order then you should watch Zero-One after Zi-O.

Saber is the series following Zero-One so if you want to watch the Kamen Rider season in order you should watch Saber after Zero-One.

Revice is the series following Saber so if you want to watch the Kamen Rider seasons in order the you should watch Revice after Saber

Geats is the series after Revice so if you want to watch the Kamen Rider seasons in order then you should watch Geats after Revice

Gotchard is the series following Geats so if want to watch the Kamen Rider seasons in order then you should watch Gotchard after Geats.

Both have main riders based on the Japanese Rhinoceros Beetle. Both the protagonists are cheeky, Stronger in a more playful way while Kabuto is a very self confident rider. They are different as well as kabuto is the about super speed and stronger about electricity.

Both are the start of eras for Kamen rider with Kamen rider of course being the first ever rider and start of the Showa era while kuuga is the start of the heisei era

Both have main characters that make the world around them better. It feels like people's life's are improved by having met them. Both have iconography that invoke old civilization, while the ryusoulgers are part of the culture kuuga has to discover it's secrets by himself.

Both came out in the 90s while the show was off the air. They both look similar and fight multiple monsters over the course of the movie. ZO is leans more on sci-fi while J is more of a fantasy

Both feature villainous organizations where the higher ups constantly argue and one up eachother. In RX they do sever a leader while in jetman they are all trying to become the top dog

While RX is a lighter show it is still the direct sequel to black so if you want to see the next part of the story for our Kamen rider watch RX

Both have a darker overall plot but are very episodic with a lot of the episode plots being silly one offs. Lupat is sillier while black has a darker ending