Who (or should I say what?) is the coolest robot, android, or cyborg character in comics? 
 
In my opinion it's a two-way tie between ultron and amazon. 
 

bumping my own

I think I'd have to go with Ultron. All though there are so many to choice from, but he'd be at the top or near the top of my list.

I wouldn't put super adaptoid on the clist, he's a pretty good character. I don't know anything about awesome andy.. but I was never a fan of characters with the name awesome or what other crazy name inserted.

Herbie
 

Aaron Stack  
 
His robot brain needs beer....

Almost forgot Eradicator

Is Metallo a robot? he's more of a cyborg right?

Amazo and Ultron

metallo is cool too. I think he's a cyborg, but they count too. With that said I'm giving Death's Head II an honorable mention 
 
 

Oh man, I can't believe I overlooked Death's Head. He's awesome.

BUMP 

" BUMP  "

This is cool:
 

No Vision or Red Tornado?