People outside Japan, what would be your most underrated Kamen Rider series and why?

I'll go 1st.

For me, it would be Amazon Riders (AKA Kamen Rider Amazons). this wasn't really tackled by most people who are KR Fans, but this for me is one of the best Heisei Riders for its dark theme that closely resembles the Showa but a more mature tone.