Faiz is soap opera-ish, moreso than any other series. I'd say go with Hibiki so you can see a whole different side of Kamen Rider after and then after that you might wanna try Ryuki if you can find it.
Kami's got Ryuki covered for me. I'll have to wait till Agito's sources are more "outsourced" course I remember ceninant having HK subs of the full series. Better find that site.
What I'm going for is probably the one more outsourced and I really loved the Hibiki movie. For now though I'll save Hibiki for last, and I'll probably go with Faizu, not because of poll is that my torrent thing is full (getting Bouken subs off TVN) and Faiz dls are around.