That's what I like about him xD

Best - Black, hand down. It has some of the most realistic looking Kaijins.

http://img2.wikia.nocookie.net/__cb2...goatmutant.jpg
http://img3.wikia.nocookie.net/__cb2...zardmutant.jpg
http://www.ryuranger.com/UPR_Book01/...s/image025.jpg

Blade's Undeads and the Dopants from W would be next, like these two:

http://img3.wikia.nocookie.net/__cb2...olf_Undead.jpg
http://3.bp.blogspot.com/_lLsdaCVk3K...0340062237.jpg

The worst will go to the Orphenochs as they are all the same color. Don't get me wrong, it is a cool idea, but it also makes them bland looking from an image perspective. The Imagins would probably be next.

Nope, wait, Ryuki's Mirror Monsters were quite bad, but at least they were colorful.

Taboo had such an awesome design. Like a creepy beautifully designed floating shoe-woman.

She was my favorite. And I surprise no one.

Her design feels like it came out of a Shin Megami Tensei game.

I liked the Dopants, particularly the more significant ones such as Weather and Utopia. In fact, Weather and Utopia are probably my two favorite Kaijin designs in the whole franchise. As for least favorite, I wasn't a huge fan of the Yummies for the most part. Also, as much as I enjoy Gaim, I don't really care for the Kaijin designs, with the exceptions of the Overlords.

For best I'm going to have to agree with Switchblade and go with the Lords from Agito. Honorable mention to Gaim because while it doesn't have many they are all great designs.

As for worst...I don't really care. Something in Showa, I guess. Go find a series where you can clearly see the suit actor under the costume. One of those.

Does Spider-Fangire's human-form count as a design? Because I loved watching him onscreen.

This guy:

http://www001.upp.so-net.ne.jp/heian/kumo/apollo.jpg

So much to love about that design. If it was up to me, he'd have his own series...

I would watch that; Apollo Geist was great.