I REALLY want to watch a Rider series in between Gaim episodes, but I'm at a loss of what to watch...

The only Heisei shows I've yet to watch (past a few eps for some) are Kuuga, Faiz, Blade, Hibiki, Kiva, Decade and Fourze. I have no real interest in Kuuga. At all, but I'm willing to check out everyone else. Any suggestions?

Den-O? W? Agito? OOO?

I've said which ones I haven't seen. I've watched all those ones you mentioned.

Well, I thought Blade was pretty good though certain plots dragged a bit (*cough*Leangle*cough*). I really liked what I've seen of Hibiki, though I realize it's style isn't everyone's thing.

Kiva's just...bizarre.

I loved Hibiki and Fourze was a lot of fun.

I love Faiz, Blade, Kiva, and Decade. I'd go with any of those.

Watched Agito 7 and enjoyed it a lot. I loved Shouichi's conversation with Hikawa and how he basically said he was Agito and Hikawa thought he was messing with him. Shouichi is really fun. The little kid with Ryou was very intriguing. Hikawa reminds me of Ichijou from Kuuga a bit, so that's a good thing. It also reminds me of Faiz, having the one girl who was connected to the 3 characters.

I'd say Blade or Fourze.

Can't go wrong with Blade.

From those which I've seen out of your list, I'd say watch Fourze. Because Space Elvis and Disco ball Bruce Lee.