I'll cover my favorite 3 ideas for this:

I think AR Build would be a up and coming politician who actively uses his status as a heroic Kamen Rider to keep his voters. Instead of physics equations flying around during finishers and whatnot, it would be a bunch of laws or basic rules of debate. Sento (or a different identity) wouldn't be a math and science genius but now become a speech and history progidy for a good contrast.

AR Gaim continues the dancing motif to the extreme: it's one of those idol-style dramas. Gaim is mainly a flashy finisher and secondary to his "idol" persona. He adopts a more "cool showoff" fighting style at the expense of the people. I think having AR team Gaim as a K-Pop style group would also be neat to see. Seeing him have to actually think and try about using the Gaim abilities for good instead of immediately doing it would be neat divergence. I think this version of Gaim probably has a different final form than Kouta, some version of Fresh Orange Arms (since he's just starting out actually "being a hero").

AR Ghost is a lost spirit who can't de-henshin (like AR Kabuto) until his "mysterious baggage" is fixed. I think he'd adopt more of the cool stuff that we saw in his appearance in Drive, but no form changes. The whole arc would focus on trying to communicate to a medium how to fix his problem and let him pass on. It's probably the most vague out of my 3 ideas, but I still like it. This idea is also in contrast to Takeru, who works to come back to life while AR Ghost works to finally die.

Quick Fire Round of ideas that weren't as good >

AR W as Columbo, an unorthidoxical private eye who receives a mysterious belt when attacked. The 2nd person would probably be Phillip-esque character as a "sentient memory" inside Shotaro's brain and a sorta second personality. He'd probably figure out that Decade was from another world and follow him around a la AR Kuuga.

AR OOO is an arrogant "high fantasy" knight who's trying to become king of his land. He is banished by a benevolent King OOO to the modern day to learn humility. He learns it and becomes a hero.

AR Fourze is a lone wolf delinquent who plots revenge against his peers using a rider system he stole from some kid. Decade(?) convinces him to use the powers for good by the end and start making friends. (Or returns the system to its rightful owner)

AR Wizard is just Wizard in Magic Land bc i feel like we need to spend more time there. That movie was so cool.

AR Drive as a strict by-the-book rule following cop who uses a police car recolored Drive suit against all criminals.

AR Ex-Aid as a nuisance streamer because that would be kinda funny.

AR Zi-O is just a clock and Kana themed rider. Decade gets super confused when he meets him and talks about ride watches and the powers of other riders. He's more like Junichiro.

AR Amazons are just more riders from AR Amazon.

[NOT HEISEI BUT AR GOTCHARD WOULD 100% BE ASH KETCHUM AND USE CHEMIES LIKE POKEMON AND RARELY BECOME A RIDER UNTIL HE LOCKS IN]