Just a few cases for DOD being their second best:
1) Best lyrics of any Maiden album as a whole.
2) Most variety of any Reunion Era disc.
3) Paschendale is their third-best song ever.
4) Every song is very good - that's 11 very good songs, more than any other Maiden album can boast.
There are others, but I'm tired/brain-zapped.
Mortals are mortar and life is the fuse.