Hm, I love Fear Factory- Demanufacture, Soul, and Fear is the Mindkiller, are three of the best metal albums I own- in my opinion of course. Obsolete isnt the greates, but the back end of the album is much better than the beginning- and its still pretty good. Digimortal is antioher story- well it does suck. Remanufacture isnt as bad as I think you are making it to be- remember this is a metal band attempting to infuse techno, electronic.
I also have alot of respect for Grand Declaration of War, it is a step in a new direction for Mayhem- and it sounds like a war march with Hellhammer's drumming- although the voice overs, the meaningless tracks etc. i can see why many think it is awful. I am reminded of a quote by I think it was Laurence Olivier about Peter O'toole's performance of hamlet, he said to be that shockingly bad, takes genius. I think this sort of relates to Grand Declaration of war.