I LOVE KORN! So maybe I can help you.
I recommend:
Issues, Follow The Leader and probably their BEST OF Album.
I'll outline each of their albums:
Follow the Leader: This was like their breakthrough album. I think it was their most popular album as well, and for me it is one of my favourite Korn Albums. It contains their hit single Freak on a Leash, which is really popular, even though it's not my favourite.
Issues, If you really like all that death in songs, then I promise you'll love Issues!
It's jampacked with full on death music, and really deep voices, which really give this album a great feel, and has such great album flow!
Greatest Hits, Volume 1, Their Best of album, has the best songs ever by Korn. I think all these songs are awesome except Another Brick in the Wall...