Dungeons & Dragons" (no qualifier)
While I like that intent, and think that branding should most likely be done that way (just as it has for prior editions), it does need a descriptor for practical reasons -- as others have mentioned, that name alone is larger than any edition and people will want a way to refer to the specific current ruleset in discussions.
I mean, you can't have a technical discussion about what's wrong with your computer's operating system by just identifying the operations system name. You need to mention what version it is if you want people to understand the baseline for your discussion. So market it as D&D but it needs a name and it's better that the company gives it that name rather than one evolving unofficially.
This just sounds uninspired and does not evoke any sort of excitement from me.
Even if this isn't the "official" name, if the new name is too clunky this will probably be the mainstream name.
"D&D 2013" (or 2014, or whenever)
From a business standpoint, branding a game with a date automatically puts it in the "kids who like the shiny new will not want it by 2015" I don't see this being a good name for that and other reasons.
"D&D Anniversary Edition"
Out of all the predefined choices on this poll, this is the one I like the most.
I have no idea what the game mechanics are like, but will it really be the ultimate final edition, ever? I suspect not...plus, it doesn't really roll off your tongue in conversation, "Yeah, i'm playing d&d, we're playing final".... wouldn't roll off my tongue anyway.
I dislike the word ultimate as way too many things are "ultimate" "extreme" and so on. and just seems like pandering to a lower audience.
I see the word Generations like that and I start thinking of a certain Star Trek movie.
See my comment above about "ultimate"
I'm a maybe on this ...
D&D Legends
D&D VE (as in roman numeral 5 edition)
D&D XLe (as in roman 40 edition) -- but "xl" is seen too much on clothing sizes that it might give the wrong meaning to someone who isn't familiar with the game, so maybe not so much
D&D LE (aka Limited Edition)
D&D Open Source Edition <-- based on the way I see it described so far

But alas, I think only tech geeks would get that reference
D&D Community Edition
D&D Freedom Edition <-- i keep seeing the term "you're free to pick your level of complexity ..."
D&D Nova edition
D&D Now
D&D: Satans Game
D&D The Heroic Edition <- only reason i don't like this one as much is that Heroic has just been added to the lexicon of the game for having a specific meaning already
D&D The One
Ring Edition
D&D The Adventure Edition
D&D Titan edition
(( Yes, some of those are meant as a joke ))
But in truth, without having any idea what the game is supposed to be like... any title i vote for would be more of a current whim rather than what the edition feels like.