My personal thougths so far, if nobody minds me putting them out there: (and these don't include my mech, by the way, and also it is including Flickr names, not forum names)
Best DC mech: madLEGOman's "N.O.R.A."
Best Marvel mech: Zane_Houston's "Atlas".
Best DC minifig: I think it's Fat_Tony_1138's "Mr.Mxyzptlk".
Best Marvel Minifig: SPARKART's "M.O.D.O.K."
Best mech: madLEGOman's "N.O.R.A."
Best Minifig: SPARKART's "M.O.D.O.K."
Second best DC mech: a tie between MacLane's "Wonder Woman's Invisible Mech" and
[email protected]' "Raven's Shadow Beast."
Second best Marvel mech: The_Lantern_Rouge's "Hulkbuster Hawkeye".
And I have to add, the 4th best DC mech: Bartosza6m_(war-C)'s "Mad Hatter's Mech".