I think the dilemma can be anwsered by 2 main question:
Do you want to tank as an off spec ?? if yes than go DH. DH bring the flex of tanking witch is great if you want to Q faster for dungeon or if your raid team needs an extra tank sometime,, if you mostly want to dps and can have a tank alt or you don't mind doing only dps than go to question 2.
Are you ready to keep more than one artefact wepon up to date ?? if no go DH, if yes go rogue.
Pure class alwayse have the advantage of more flexibilty as they can chose the spec that fit the fight the best. They also have a tendency to be a bit better than hybride spec in avarage over a full tier as they most of the time have a really good ST and a really good AoE spec. We can't see the futur but if we look at WoD overall best spec
3 pure are in top 3 ST dmg with arcane mage, sub rogue, afli lock.
4 pure are strong in 2-3 target cleave, combat rogue, frost mage, destro locks, marks hunter
4 pure are strong in big AoE , combat rogue, fire mage, destro/demo locks, Bm hunter
DH might be strong in AoE or ST but it's rare for a single spec to perform in top 5 for ST, Cleave and AoE tho it's not rare for pure classe to be in that situation.
If you want to dps all the expac and if you want a good chance of toping meter on more than the one or two fight that fit perfectly for your dps niche, rolling with a pure like rogue is probably a better choice than rolling with a DH.
If you care about looks or lore over dps and ulitity than go with whatever you like XD.
Every time i ask myself do i want to keep my rogue main...
and i stay rogue... cause they are the most badass class in the game!