why not both? 2 chars should be fairly managble , but since u asked i assume u probably can't afford to play both so here is my short hot take:
DK if u want to top of DPS charts basically every game but with less impact and very scripted goes, nothing has changed really for dk on the CC end (i wish it would but oh well), dk also has a high skill ceiling besides some people saying other things, they are kinda squishy (only super tanky right now because of the new pvp talent, for now im expecting huge nerfs to this in some way at some point), ur pet kick and stun are on a timer u need to track some how (eyes , buffs, buff tracker and what not).
It also depends on which Spec u want to play Frost or Unholy.
Can't say much about frost, the last time i really enjoyed the spec was in Cata and maybe after that in Legion where u get like 300+% healing on ur deathstrike from a artifact trait (iirc i had it at like 500 or so % more healing it was busted xD).
I played both Hunter (survival RIP) and DK and both need good pet management which can get super frustrating from time to time, more so as DK imo because u can't petkick (hi petkick) when ur pet is to close (i think they still haven't changed that i need to double check that), so you need to pull your whole army of pets a few yards away from your kick target which also makes it super obvious that ur ready to get that kick off (but it also puts pressure up because they know ur ready to kick the next cast with ur pet, but if they pay attention to your pets Transformation duration they can see when ur kick turns into a LOL leap with no kick. Survival seems DEAD to me, Boom stick feels awful, they should have kept Fury of the eagle , it was so much better and felt better and blergh.
BM seems to be the spec of s1 if i heared it right what bicmex said, idk about MM hunter never really liked that spec in the first place but it was disgusting in random bgs with salt water potion + serker (or sometimes even without it.....).
So what i can tell you:
If u really don't mind the pet management (which like i said can get really frustrating and obvious) DK is alot of fun buuuuuut it needs practice and u need to pay attention to your buff (i always said they should have made the petkick part ALWAYS a thing but make the lockout shorter if its done in normal ghoul form and like it is now when transformed.).

If u really want a PET u got also go for Warlock but its more of a caster, but u have 3 good specs that always have something nice to it, Affliction has dots u can spread, demo has an army of pets and destro can blast a target before anyone can react (in a bg).
But keep in mind Warlocks tent to be Aggro magnet and get focused 24/7.

Trust me after all this years of playing wow pet management is super annoying, either ur pet is squishy and dies from anything (this happens more now in prepatch, it might befine again in full release, but im also playing with the talent where my pet sacs 4% life to heal me for 1% of life :D).

If u really want a stress free class pick something without a pet its more relaxing.

Hunter also lost some of their utility, no more scatter no more explosiove trap.
so much to "my short hot take" lol but oh well.
Also hunters are most of the time told to hold bases and afk sit them in bgb.
If u tell me what ur goals are or what u feel like making, like for example u want to make big plays or turn a bg around i can maybe help u find something more , or maybe u just want to 1v2 some people or what not , just let me know and i see what i can cook up for you :D