Indeed, a very hard decision. But fortunately Blizzard gives us a subtle hint, here:

Yep, I know I might be wrong, but I think this is a really good starting point in choosing your character’s race.

Blizzard is showing a good deal of common sense when displaying these pictures. Think about it: Rogues benefit mostly from Dwarf racials, same with Druids (Taurens) and Hunters (Night Elfs) (Shadowmeld/Prowl FTW) and basically all races are drawn to match their best equivalent class.

Interesting fact: Blood Elfs are nowhere to be found *giggles*.

Also, it appears that the class to make your Death Night will be a Draenei. Anyone want to comment on that?