for Vital Remains...Dechristianize is definitely the must-have. Anyone interested in death metal should have a copy. Absolutely masterful.
After that, Let Us Prey is also quite excellent. Forever Underground and Into Cold Darkness are both damn solid death metal albums featuring relatively lengthy songs that help them stand out from other old school death metal bands. Icons of Evil is pretty much a regurgitation of Dechristianize, and while there's some excellent parts on there, the songwriting is much weaker and they seem to be using Suzuki's lead playing as a crutch rather than a tool. Worth having, but the others are all better. I can't comment on Dawn of the Apocalypse, as I haven't heard it.