You've seen pretty much all Heisei Riders, so I say it's time to go Showa! Black and Amazon are personal favorites of mine, and I always recommend them. Though Amazon might be a little weird...
Sentai-wise, you can't go wrong with Changeman and Dairanger. I also like Gekiranger a lot.
Kamen Rider: Blade/Kabuto/W are pretty good series to watch if you want a sort of dark story
Den-O if you want a comedic story with some dark elements in it.
Kiva if you like emo Riders who start to become one with society or something like that
Decade if you want a Micheal Bay series of Kamen Rider that is short yet okay in a way
Super Sentai: Magiranger/Gekiranger/Go-Onger if you want a comedic story with some dark elements in it but, not as much.
Shinkenger/Dekaranger for dark serious stories that only happen at somewhat the end but, is still put into the whole show from the beginning.