So anyone that I know is excited about the whole Transmogrification coming with 4.3. That is everyone besides Deathknights who for the most part think they are getting screwed over with the system. The problem being they haven't existed since the beginning of WoW and their choices of sets to use is very minimal. The other problem or issue they have stated is that their sets all look very similar. So even if they decided on a past set to use they really wouldn't look that different. I really understand this argument, but a Deathknight is not really a class that you can make a colourful set for. It just doesn't fit with lore and the actual model of the class. Some of you will say what about a Warlock? And I will say that model or design still isn't even close to the same. Yes, warlocks use dark magics, but there is nothing stated in lore saying they are anything close to a former scourge being.
So what are the Deathknights choice? Well they could just wear the current tier or suck it up and use past tier sets and realize that is what the class they chose is all about. Rades over at Orcish Army Knife even has a layout today about not tier plate sets you can take a look at. If that is something you are interested in. You can see that post here. Check it out a lot of time and effort went into developing it.
The other option is to do what the Daily Blink suggests
Sorry Deathknights for causing laughs at your expense.