There was already a thread on this back in the day (
here). But then again, it's riddled with posts I made years ago where I really needed to chill out about things that don't really matter, so maybe it should stay forgotten
But to bring up a few:
I really liked Den-O and Black RX, two seasons that seem to get a lot of hate. On the other hand, I really
did not enjoy Agito. It's not quite my least-favorite Rider series (Faiz and the second season of Amazons immediately come to mind as being worse) but it seems to be a lot of fans' favorite season and it's nowhere near that for me.
Foundation X were rubbish in Double and I disliked all the attempts to bring them back.
Kyoryuger is the only toku series that has given me the same beyond-excited feeling that I had watching MMPR as a little kid, so for that alone it's my favorite Sentai.
When I was first getting into toku, it seemed like everyone hated Magi Pink and Deka Pink, but I thought they were front-runners for best members of their respective teams. Similarly, people seemed to despise Gosei Red but I thought he was interesting too, if not a favorite.
I thought Kikaider was pretty crap tbh and yet somehow it spawned a (minor) franchise. ¯\_(ツ)_/¯
Kamen Rider Decade might not be good, but it's not nearly as bad as people make it out it be. Could be better, but still not that bad.
I always say that Decade was a great "shop window" for showing off the previous Riders' suits and powers. Some great music and great fights too. One of the best opening episodes to a Rider series. I even think the plot works quite well as they go through the initial nine worlds, even if it does go to pieces afterwards. Oh, and it's World of Amazon is better than either the original Showa Amazon or recent Amazons TV series.