Obliteration split cd w/ Macronympha - one of the earliest noise releases i owned, this is totally killer. mandatory, unstoppable, violent, fast paced harsh noise mastered by roemer for extra layer of grime. Swaps places with some other classics at the very top of my all-time favorite harsh noise list.
along those lines "The Maternity Music" c60 which i think has since been re-released is essential GA
Alphaville LP, yep
"Sporatic Spectra" praised often as one of the loudest cd's ever produced, but should be also for its brick-splitting heavyness executed with surgical precision...it'll give you that harsh noise hit of crack head high for sure.
"Bloody Slumber Party" - just as good as "The Maternity Music" !!! pretty impossible to find though.
really can't go wrong with govt.alpha (though i have not followed much after the early 2000s - what i have hasn't shown a decrease in quality) but these will always stand out as the special ones to me. should be noted that i thoroughly enjoyed the 'Structural Contradiction" 3x-cs that got traded to me recently though...still at it, still a master.
to somewhat echo earlier responses - it is fucking impossible to even find mp3s of old GA/Xerxes so unless Yasutoshi is in the Pain Jerk camp of letting those sleeping dogs lie, someone needs to get another box like the Pica Disc one together. Personally I prefer re-isssue box sets to include the original work in its entirety so i have yet to pick up that set on Pica... skipping all over the place is a turn off to me... but I guess when there is no other way, I'll pull the trigger eventually.