Kamen Rider Super-1 (1980)

Black is the series after Super-1 so if you want to watch the Kamen Rider seasons in order watch Black after Super-1.

Super-1 is the sequel to skyrider both feature riders who are cool and level headed. Super-1 more unique thing with it's multi hands and focus on marshal arts but both end up as a basic Kamen rider series

Both are series with a surface level space theme while changeman does more with having the go into space in the end while super-1 was training to be a astronaut before he became a cyborg