Honestly, I think the Rebels will laugh when they hear this name. "Death Star, oooo, I'm so scared by the big mean Imperials who use metaphors so clunky they bash you over the head with it."
If we're going by traditional Imperial naming conventions, it should either be a self-descriptive noun combined with an adjective or an acronym.
How about Death S.T.A.R (Station Targeting All Rebels), like T.I.E. Fighters (or the new T.I.E. Interceptors)?
Or Fear Station? Isn't that the equivalent of Imperial Shuttle?
You know what they should have done? Hired the best writers in Coruscant to come up with a name.
The one exception to this rule is Star Destroyer. It's still kind of a weak metaphor, but it has a nice ring to it. Star Destroyer, as in "one who destroys stars." Now, these ships don't actually destroy stars per se, but we do blow lots of stuff up, either through our turbolasers or our fleets of Tie Fighters. Hence, the name fits. But this station is supposed to be a number of things - a station, a giant floating gun, the place where the Imperial Life Day party is held. Seriously, who wants to go to the company Life Day party at a place called the "Death Star"? That just takes all the fun out of it.
But I digress. I suppose I'm not as clever as Vader (rumor has it, he came up with the name - hey Darth, you're not the most eloquent person and you sure throw hissy fits when you don't get your way), but I'd pick a name that was more elegant.
In any case, we will be hyperspaced over to the "Death Star" in two weeks. I gotta start packing my things up and taking holo-pics of my buddies. Good times, good times.