Took from Reddit:
Gaim - God. Golden Fruit's only known weaknesses are limited time travel and being unable to revive the dead. He is divine with many varying abilities, barely tapped into correctly in the series or even the movies. He is by far one of the most powerful beings in the Multiverse. Terraforming planets, crossing different universes etc.
Decade - An obvious choice. He possesses abilities of every Kamen Rider now from Kuuga to Build(Even Zi-O). Including the advantage of mix and matching each of their abilities within their standard states. Just his very existence is capable of bringing down Multiverses and he's literally the destroyer of worlds. Dude is insane.
Ex-Aid - Aside from the Gamer Drivers being some of the most BROKEN pieces of technology ever and the energy items being CLUTCH, you have Invincibility. God-like gamer powers materializing into the real world effectively. Even Maximum Gamer God Genm who SWUNG THE MOON AROUND wouldn't be able to beat him according to Emu. Truly an absurd final form. Mighty Creator VRX and Mighty Novel X are also no joke in the slightest.
OOO's - One of the most artillery gifted Riders of all time. The scariest thing about OOO's is that the fact that the animal theme and abilities associated with them are but just the layer of his abilities. He has no energy source or limit to his abilities (At this point) Because OOO's is powered by Desire and Alchemy. OOO's catalyst for his powers is a concept. Hence why he can erase things from existence, create unlimited clones of himself, slice dimensions, stop time etc. OOO's isn't a divine Rider but he has the power to /break/ divinity. OOO's is one of those riders who can and will be capable of giving a fight to anyone. A wide array of haxed powers and such and immense strength and potential. The Rider who is "Beyond Infinity"
Ghost - Another divine Rider here. An Angelic being who's powers surpass humanity at its peak. The infinite potential of the human race personified and embodied beyond comprehension. Using the abilities of the emotions for attacks. Mugen Damashii is frightening because of its growth and adaptability. Casually defeating Deity's and never ONCE losing a fight (Except for the Bugster, however Takeru was infected by 2 different gamer viruses at the time and they made it clear that the ghost virus was especially potent) Is also very arsenal gifted
Wizard - Versatility to the maximum. Magic being one of those fictional abilities that you can abuse to whatever you liking is due to how flexible and forgiving "Magic" is. We've even seen Haruto travel through time for crying out loud. In an inferior form he's kicked somebody from the earth to the Sun within 12 seconds. Infinity having some of the most absurd defense and offense I've ever seen. Even dimension slicing abilities being useless.
Kabuto - One of the most OP abilities involving timestop I have ever seen minus the Flash's. He traveled to the edge of the universe in seconds. Exists outside of Time's laws. Can stop, slow down and reverse time. Even strong enough to kick Giant world-ending meteors away. Not to mention the man underneath the suit itself. Tendou Souji. A Gary-Stu done right. Being a perfect hand to hand expert, analyzer, competitor and one of the strongest wills ever. The man underneath the suit is what makes these absurd powers scary. He who walks the path of heaven rises above all else.
Kuuga - The man man with 2000 skills. The endurance freak of Heisei and the smiling protector of all. Kuuga is versatile and his skill level is MASSIVE. I've never seen a Rider take as much on screen punishment as he has and gotten right back up from what I can remember. Kuuga is raw force and the skill to match up behind it. His Ultimate Form is even threatened to be something which can end the world itself. Yusuke Godai is a force to be reckoned with.
Agito - Evolution. For many similar reasons of Kuuga up above. Agito is incredibly powerful, incredibly versatile and damn he is a good combatant. His powers evolve and reflect his inner self. From the burning fury of his burning form to the the added evolution of his burning form. Shining and commanding with the power of the sun itself. Agito also has one of the strongest Rider Kicks by far. He defeated an overlord with the ability to manipulate a star as well.
Blade - What can I really say? The guy is immortal. He cannot die to the usual means and sealing would be your best bet. He has the powers of the undead merged into him and his King Form. One of these powers include an undead with the ability to stop time as well. He's even showcased the ability to cross dimensions and I'm pretty sure its been stated to if he died it would cause the end of the world. Blade is ridiculous due to the circumstances his abilities create.
and from my own opinion:
Zi-O - The Power of all the Heisei Rider Combine, able to one shoot all the final boss from all the heisei series.
