Stark Sentry.

I really like the shaping and humanness

to this mech, built by Magus.

The round armor pieces are a nice touch.

I can imagine a dozen of these guys taking down a Sci-fi Fortress somewhere. :)

See it on Flickr.   

Robo Gold

halfbeak (on Flickr) has constructed a very cool little MOC! The parts usage here is fantastic! Especially the tank treads as flooring. The robots themselves are very nicely made as well. Be sure to check it out on Flickr.

Optimal Defense Droid ZR3

Chris, AKA Iornsniper on Flickr, makes some fantastic robots and exo-suits, and his latest one is no exception. 

I love the combination of a square head and unique legs.

Be sure to check it out on Flickr.