1. Paragon
2. Fathom
3. Medusa
4. Viking
5. KISS
Special mention ;
Spirit
Ah Fathom! I forgot about Fathom, another stunner. Don't know how I forgot it though since I just ordered this back glass through CPR (just need the matching machine now).
You can't really underestimate how important they are to a game either. I guess they're just like a book cover in a lot of ways, though the saying goes "don't judge a book by its cover" it's certainly where we get our first impressions of a game. In many cases its what attracts us to a game in the first place. For me the original artworks are the best ones.