Blaze's solo albums are great. 'The X Factor' is great. All of Bruce's solo albums are great.
Does Blaze compare to Bruce as a vocalist? No. Is Blaze still a great vocalist? Yes. Is the Blaze-era Maiden stuff as good as the Bruce-era stuff? Some of it. Not all. Is it as good as the Di'Anno-era stuff? Most of it, not all.
The three things should always be considered separately. Unless you're Journey and try to hire a clone of your most popular singer, when you change vocalist you change your sound, and the new sound should be considered on its own with one simple question "is it a good album?" The question of "is this as good as the old albums?" should never be asked when considering the quality of the album, only as a discussion point.
And that's why 'Death Magnetic' is awesome, and you all suck.
Wait... different argument