I'm going to rain on the parade here and say that while Kuuga was enjoyable enough for me, I have never had to watch something as unpleasant as Agito before or since. It's like they took all the good aspects from Kuuga and ruined them.

In response to Agito discussion: I'm currently in the middle of episode 49 and Agito hasn't done too much for me. It's a bit better as of 40-ish, but most of the series seems like a lot of messing around with unimportant subplots that provide a tiny trickle of what the bigger picture is, and monster of the week plots with said monsters being wholly uninteresting.

The biggest criticism of Kuuga I've seen is that there isn't enough plot, but that's probably the main reason Agito has been kind of falling flat for me. At least with Kuuga you get to see the Grongi talking and hints of what they're doing, but in Agito you don't really know anything for a long time except monsters are attacking certain people and some weird characters who are maybe evil or maybe not are saying weird things to each other and doing weird stuff.
I like Kuuga more because the Grongi are a lot more interesting as monsters of the week and Kuuga's form changes and belt are much better than Agito's. Although I'm different because the belt and gimmicks are pretty big factors in how much I like a show, which is why I'm more interested in Faiz than Ryuki even though I'm know the latter is better.

Here's a rundown of my problems with Agito:
-Shouchi/Agito is a bland and uninteresting protagonist. Hikawa/G3 and Ryou/Gills both have more depth and motivation than Shouichi
-Almost all of the plot elements are either explained very late in the show or aren't explained at all. Many of the things brought up at the beginning of the show are never discussed again.
-Nearly half the show is pointless filler. There's no plot advancement or character development at all.
-That stupid love triangle that takes up like ten episodes.
-The villains are extremely underdeveloped.
-At times the characters' plots feel all over the place, with groups of characters disappearing for episodes at a time.

Honestly the only good episodes are maybe the first ten and then 30-45. The last 5 or so episodes are pretty bad.

Now, I'm pretty new to this Kamen Rider business. I've watched several episodes of W, OOO, and Fourze, and all three of those use the two-episode story format. I've read that Gaim doesn't. Do all of the Heisei riders before Gaim do the two episode thing? Or just W through Wizard?

It started becoming popular around Den-O, and once W hit it was THE format. Gaim went away from it, and now Drive and Ghost alternate between both formats.

Which leads into my next question. Which series have the heaviest use of the MOTW format, and which ones tend to stray from it?

A lot of the Pre-Decade Heisei series don't really use it beyond Den-O. A lot of them tend to stick to MOTW while furthering their plot.

I feel Kuuga made the heaviest use of MOTW. I also want to say Kabuto and Kiva, but it's been so long since I've seen them I can't properly remember.
I think Gaim and Hibiki strayed from it the most.

Most of the older shows at least had monsters that were around for two episodes, but generally there were a lot of ongoing storylines and developments that ran alongside the more fortnight-y aspects. Den-O was the show that really introduced the format of focusing mainly on a single monster targetting a specific guest star for two episodes.

Do you like the idea of a villainous Billionaire Kamen Rider?

Since there's no main Kamen rider who is a billionaire, I thought it would be interesting idea since we haven't got a billionaire-type Kamen Rider who is a villain. Since he is a billionaire, What if he pay out all Evil Kamen Rider to be on his side and beat the crap out of Main Kamen Rider like when Triple H put a bounty on Goldberg in order to regain his World Heavyweight Championship. So basically this billionaire Kamen Rider put a bounty on Main Goody Two Shoes Kamen Rider like Kouta. Instead relay on monster of the week or Sentai-type foot soldier, Why not have him flash the cash on and get every evil Kamen rider on his side! He will says

"I WANT KOUTA DEAD! I WANT HIM BLOODIED AS HELL! Get Him! Get Him!"

Who like the idea of a villainous billionaire Kamen Rider pay all Evil Kamen Rider to beat the crap out of a goody two shoes Main Kamen Rider

Wasn't Ryouma pretty wealthy?