best kamen rider kaijin designs?

[Kamen rider sol]

for me I would say the undead, they look menacing and cool especially the eagle undead

 

[Scissors]

The mutants in Black were pure nightmare fuel. The Spider Mutants still scare the crap out of me. So I think their designs worked really well.

Then there were Goushima from Shin and Doras from ZO who were just beautiful to look at. The amount of details on those suits were insane.

 

[Bryd0]

To me, the Fangires, Phantoms, Orphenoch, Undead and Worm have all got good designs on them.

 

[rising7]

The Unknown/Lords from Agito were pretty great. I enjoyed how they looked like people wearing animal masks, and in some cases like the Crows resembled skeletons. Though curiously I didn't like the El Lords very much in comparison.