Dr Doom vs Apocalypse
I think this would be a real one sided match. To me it is obvious who will win just looking at the past fights that have occured. Doom has beaten Galactus. DC's Darkside's Beams couldnt hurt Galactus but those same beams would destroy the hell out of Apocalypse. Doom has his own planet and is a universal threat. Hell Magneto is in between the 2 in power as well. These guys are in 2 different leauges.
Doom takes this IMO