Yeah, both discs have flaws - but the Optimum is by far the better option. And I'd go so far as to recommend picking it up. The transfer is slightly cropped (zoomed in) - though not all shots are affected, and a couple actually feature more picture information than the Elite master.
It's a beautiful looking transfer (restored by Don May Jr. who also worked on the HD Texas Chainsaw Massacre) and an absolute revelation compared to the Elite disc.
Also worth noting is the fact that Romero himself approved the Optimum master - the cropping doesn't really harm the compositions (imo) because the full 1.33:1 frame features quite a bit of dead space. Also, the original mono track is included in lossless DTS-MA form, and the included documentary is excellent.
As Daemonia has said, the Network disc is very dodgy, which extremely high contrast and major print damage.
Check out the comparison here between the Optimum blu-ray and the Elite dvd:
caps-a-holic