>>23529229
Typically I think people recommend phase 2 Heisei because they are the style that Rider is done nowadays.
Early Heisei had a very distinct tone but Den-O was such a huge paradigm shift. Ryuki is an amazing series but it's so different from everything else it's a bit rough to recommend as an introduction to "what Kamen Rider is."
"Watch what seems cool" is also a fine experience but of course that comes with the caveats that there are some series that have amazing aesthetics but lackluster writing.