[Handle Ken]

I have alot, so here is a list by order of series:
Kamen Rider
Let's go rider kick, original, rider girls and rider chips.

Kamen Rider ZX
Dragon Road!

Kamen Rider Agito
Deep Breath and Believe Yourself from agito, definitely. Agito's bike, Machine Tornador, also has a very awesome named after it.

Kamen Rider Ryuki
Boundless Life

Kamen Rider Faiz
People with no name is an obvious choice.

Kamen Rider Den-O
Double Action Gun/Wing/Rod
Climax Jump Den-liner form and Gun form
Double Action Climax form GUN-rap (If you can't tell, I like gun form-related songs really much, especially the rap)

Kamen Rider Kiva
This love never ends is such a beautiful song
Supernova.

Kamen Rider Double
W, you know, the song by Eternal's actor.

Kamen Rider OOO
Power to Tearer and Time Judged All are my favorite combo songs.

Kamen Rider Fourze
Hayasuba-chan is cutest song ever.
Saite makes me sweat through my eyes everytime.

Kamen Rider Wizard
Beast Bite and Last Engage. Not much comment here

Kamen Rider Gaim
E.X.A is very upbeat even though the lyric is pretty grim.
Rise up your flags is a very strong song for a strong form
Ranbu escalation is a duet by main and secondary riders, pretty cool if you ask me.

Kamen Rider Drive
Full Throttle, Mach's theme.
Spinning Wheel, which beat ranbu escalation by having the tertiary rider singing too.

Kamen Rider Ghost
Harp-y4's song in episode 35-36 is pretty catchy.
Since the series doesn't have many songs, Alain's heroic OST counts right?

Kamen Rider Amazons
Armour Zone is awesome, beastly and catchy.
Die Set Down is no slouch either, though sometimes when the episode ends with some serious scene and the singer screaming "WOAH WOAH WOAH WOAH WOAH WOAH" is kinda goofy.
Iyu and her dad's theme. It is creepy, but also sad and heartwarming at the same time, not to mention how it is related to their family name (Hoshino).

Kamen Rider Ex-aid:
Excite, Wish in the dark and People Game.