This is just a for fun question, if you feel the need to you can also go into what specs of a class would slot into (for example a frost mage favoring frost DK but maybe other specs of mages into other kinds?).
So what kind of deathknight would your class be?
I am Rabies the Magnificent, I cannot be killed.
But should such an unfortunate event happen. I am dammned sure i will return as a Blood Deathknight. Like the Cockroach i will be verry verry hard to kill even beyond death!( And thinking i do alot of damage, but lets face it, i dont, i just dont die)
Funnily enough, I finally leveled a character to 10 on a US starter account so I could post on their forums as well, and when deciding what to play I went with my previous life 
I’ve honestly no idea if a Demon Hunter can be raised as a dk, but I guess if they were they’d probably be either Blood or Unholy?
Their whole fire aesthetic means Frost is unlikely.
Unholy is a definite possibility; The Scourge was itself originally created by the Legion, so there’s a potential link between fel magic and necromancy.
On the other hand, Blood dks draw on the essence and life force of their enemies to sustain them, which fits rather well with Demon Hunters who do more or less the same thing, but with souls instead of blood.
It’s interesting, because dhs an dks actually have a surprising amount in common: they’re both driven and sustained by their hatred; both use the powers of their enemies against them, powers which are considered anathema by most; both outcasts and both irreparably changed by becoming what they are. But for all that the classes are similar, there aren’t obvious parallels with dk specs in the way that, say, Holy Paladins or Frost Mages have.
Definitely a Blood DK. I am already leeching the life force of my foes, undeath will further improve that.
This is the way of the San’layn. Beware my fangs, lest you suffer the kiss of a vampire.
No. DHs cannot be raised in undeath due to their demonic nature.
Hunters will be raised as that skeleton with the bow that you can summon if you spec that one talent in unholy tree
Mage would be Frost. The Lich King even Ice Blocks Tirion on top of ICC, why can’t Frost DKs do this now?
Any DW class/spec - Frost
Casters - Unholy
Tanks - Blood
Frost mages - Frost
Holy paladins - Unholy
Other paladins - Whatever they want except DW frost (2H only)
Hunters - Unholy because how are they gonna manage with no pet?
Aren’t demon hunters canonically immortal? In legion, Illidan basically says “Oh, you’re the same as I am, you can’t die! That’s convenient!”
They can on multiple targets too lol
Blood for me!
So I can become a San’layn
All lesser death knights are mere maggots compared to me, so it doesn’t matter what race/class etc etc.
I am completely irreplaceable, and completely unique. The one and only.
Frost dual wield all the way… I can make my own popsicles
I’ll become bdk so that I can be top on healing.
wait… you mean Im not an Unholy Death Knight???
It’s more complex than that. Every dh exist on a spectrum between mortal and demon. When a living being is subject to fel energy it can either destroy it or slowly turn it into a demon, that’s what happened to the eredars for example. This process is characterized by the developpement of mutations that become more and more prononced as the subject is exposed to more fel energy or as time goes on.
Dhs are exposed to an incredible amount of fel very quickly during their initiation ceremony, which is what makes this ritual so deadly. For a mortal to be turned into a demon it usually need a slow exposure gradually building up, because a too violent exposition is likely to kill the subject. This is why the ritual also includes defensive measures, such as gouging out the iniate’s eyes to lower the impact on the mind, or the tattooing of the body with magical inscriptions to help contain the energy.
In effect, a dh is subject to an accelerated evolution to demonhood, which leads them to becoming more and more demonic in appearance as time goes on. Furthermore, as in the name suggests dh actively hunt demons to slay them and absorb their souls, leading to even more exposure to the fel and mutations.
This makes illidaris exist on a delicate balance, as they seek to kill demons to absorb their souls to grow their power, but the more powerful they become the more demonic. This is dangeours for two reasons, first it might very well kill the dh who could become overwhelmed after absorbing too much fel energy. Or it could be more insidious, demons are destructive and self centered creatures and the more demonic a dh becomes the more it alters and twist their personnality this way. As such, a dh might very well loose interest in the cause of the illidaris and join the legion or strike out on it’s own, or become overwhelmed by bloodlust and go on a rampage. This is the crux of the moral dilemna around the class, how can we be certain they seek power to do good, like destroying the legion, and not simply because they have become so demonic themselves they are just power hungry ?
The vast majorities of dh are technically still mortal however. We know that Illidan is now technically a demon, as his soul’s returns to the Twisting Nether when he dies, and we know it is the same for the Slayer (the dh player character). We don’t know for sure if the Slayer is technically a demon, as his appearance is pretty similar to that of other dhs, I personnaly believe he is still but he is very close to finishing the process just like Illidan did back in WC3.
With that in mind, yes the majority of dh could be raised in undeath as they are still mortals and have souls that still obey mortal laws on life death. They are a few caviats though, indeed as their body are filled with fel energy they aren’t the most stable so the manner in which the dh died might result in his body being completly destroyed or even his soul, making his rising in undeath impossible.
Would they retain their abilities ? Hard to say for sure as we don’t really have any examples of characters that powerful in the fel being raised, however I don’t think it’s 100% impossible as we have seen characters that were strong in other powers such as the Light still able to use them as DK, although that could also be specific to the Light. The fel isn’t the only source of dh powers though, they also use shadow magic quite extensively aswell as soul magic. Their old focus on draining demon souls to sustain themselves makes me think they would most likely become Blood Death Knights.
Havoc DH would most likely end up as unholy…
But thanks to the class wide abilities we’ll steal Frost elemental from frost mages, devouring plague from Spriests and unstable affliction from affli 'cuz even in undeath a demon Hunter will do what he does best : Steal stuff from other specs.
As a druid, I’d probably be a very unhappy DK! 
But if I had to pick, I guess unholy since spreading diseases is the closest thing to spreading ‘nature’ damage? 
Basically a blight druid from pathfinder, spreading rot and decay while making friends with pests and bugs. Also shrooms, lot of shrooms.
Holy Priestess of the Shal’dorei.
Let’s go Unholy Death Knight to be controversial.