I say this because the choice doesn't just come down to your preference for art style or something; Blizzard is digging deep into the lore of the Starcraft universe on this one. Splitting hairs, even. Quoth the voting page:
The protoss dark templar has always been one of the StarCraft community's favorite units -- now, the community has a chance to participate directly in the dark templar design process for StarCraft II! Over the course of the next month, players will vote to decide which dark templar model will appear in StarCraft II multiplayer matches.
- The first option represents the Lenassa tribe of dark templar, which made its debut in the original StarCraft. This unit carries a single warp blade, and a cloth shroud covers its face.
- The second option represents the Zer'atai tribe of dark templar, who wield dual scythes and wear an ensemble of heavy armor and the bones of slain zerg.
Can't say I have much of a preference either way; both of them look equally ready to kill! In all seriousness, this is a pretty neat way to get people involved and give hardcore fans a say in something that might actually matter to them. Might as well ask: which one did you pick?
I do have a preference regarding the eventual release of Starcraft II, however, leaning decidedly toward "sooner" rather than "later."