>>23489956
Every Kamen Rider season and Super Sentai season are mostly standalone. Only ones that kind of require having seen prior seasons are Skyrider and Zi-O, in Super Sentai's case Gokaiger, but even then their story is standalone enough that you can understand the shows without any prior knowledge. So since most seasons aren't connected in any substantial way it's recommended to just pick whatever show catches your eye.
If that still seems intimidating to you then I recommend either watching ZO which is a standalone movie rather than a 40+ episode series, W because it's a good season to ease you into the usual tropes found in Kamen Rider plus it has a sequel Anime series which might be a more familiar medium to you or Kiramager which just like W is good to get used to Sentai's tropes. There's also a new Kamen Rider season called Zeztz that's starting this weekend which will be the first season to get a worldwide simulcast, according to the staff the show is being made as an entry point to bring in new viewers so you might want to keep an eye on that.

Kamen Rider and Super Sentai are made by the same Studio and sometimes the same staffers, the key difference is that Super Sentai's focus is a bunch of people coming together to defeat some villains while learning how to work as a team while Rider focuses on a single protagonist whose powers originate from an evil source. Otherwise it's whatever the staff wants.