Alliance Vanguard and Horde Expedition
The first reputations you encounter are pretty sparse, actually. Maybe the Horde and Alliance aren't so sure about this Death Knight thing after all. Still, it's worth grinding to revered for the Arcanum of the Savage Gladiator if you're planning to do any PvP. In addition, if you're a dual wielder, the honored reward Hammer of the Alliance Vanguard/Warsong Punisher may be a relatively decent off-hand choice at level 78.
The Tuskarr have a good selection of quest rewards that end up being very Death Knight friendly. You can easily get honored simply by completing all the Kalu'ak-specific quests in Howling Fjord, which will give you access to a set of plate breastplates, the Whalebone Carapace and the Ivory-Reinforced Chestguard. Both are pretty solid for their specific role, and don't have any less useful stats such as shield block and haste, so chances are you'll end up wanting to pick up one of each when you hit level 76.
In addition, once you hit revered and level 78, you'll be able to pick up the Whale-Stick Harpoon. While it doesn't have any pure strength, it does have quite a bit of attack power and agility, and it has more DPS and high-end damage than the De-Raged Waraxe, the quest reward from the Ampitheatre of Anguish that will probably end up being a Death Knight leveling staple.
You'll also want to consider finishing the grind to exalted, even though neither of the exalted rewards are specifically for Death Knights. One of them is a penguin pet, and the other is a fishing pole which comes with the side bonus of granting underwater breathing. Much like our Rogue brethren, we're locked out of using the Hydrocane, so this is a nice way for us to grab that extra bit of utility -- we may need it when we're raiding the Naga capital next expansion, right?
The Wyrmrest Accord
The Dragons at Wyrmrest are a veritable treasure trove for the beginning level 80 Death Knight tank. At honored, you can grab the Cloak of Peaceful Resolutions, and at revered you can get the Breastplate of the Solemn Council and the Sabatons of Draconic Vigor. All are pretty solid pieces that should last you until you can grab a proper heroic upgrade.
In addition, dual wielders might want to grab the Fang of Truth as an offhand weapon at honored. While it has no strength, it does have solid DPS stats otherwise, including a nice chunk of precious, precious hit rating. At exalted, you can get the Legplates of Bloody Reprisal for DPS, although the armor penetration somewhat hobbles them for Death Knight use. But hey, you're going to grind for the Red Drake anyway, so if you don't have anything better, why not?
The Argent Crusade
The Argent Crusade, despite skewing a bit too much toward armor penetration for my Death Knight tastes, still has some worthwhile rewards to grab. The Special Issue Legplates are quite solid for Death Knight tanks at honored, and at revered, you can grab the tank head enchantment, the Arcanum of the Stalwart Protector.
In the DPS arena, the Cloak of Holy Extermination's stats aren't really Death Knight focused -- it has no strength, and it has armor penetration -- but it will do in a pinch if you need a better DPS cloak and you're honored with the Crusade. At revered, you can pick up the Fang-Deflecting Faceguard, which has a lot of strength, but will be hobbled because of that armor penetration. Finally, also at revered, there's the Argent Skeleton Crusher, which is big, slow, and hard hitting, just the way a Death Knight likes it. The Strength and Stamina should make up for the Armor Penetration.
The Ebon Blade
Despite being the Death Knight faction, the Ebon Blade seems to have decided to mostly service the other classes in handing out their rewards. The honored tanking boots have shield block, for crying out loud.
The two melee weapons they offer at revered aren't really optimized for Death Knights either. The Runeblade of Demonstrable Power and the Reaper of Dark Souls both eschew strength for agility and attack power, and the Runeblade has haste, arguably the least useful melee DPS stat for a 2-handed wielding Death Knight. Still, the Reaper of Dark Souls is probably a pretty solid dual-wielding main hander anyway, and the Runeblade should still hit hard enough to make it a passable weapon if you don't have better.
Still, a couple pieces of loot may just make the rep grind worth it anyway. At revered, you'll get access to the Arcanum of Torment, the DPS head enchantment for Wrath. In addition, the Death-Inured Sabatons at Exalted are amazing Death Knight DPS boots, with strength and plenty of critical strike rating in abundance.
The Sons of Hodir
Unless you took up or plan to take up Inscription, you'll probably want to quest to exalted with these guys, as they're the shoulder enchantment faction for Wrath. At honored, you can get the Inscription of the Axe for DPS or the Inscription of the Pinnacle for tanking, and at exalted, the Greater Inscriptions of the Axe and the Pinnacle.
There's other worthwhile rewards as well. At revered, you can grab the Spaulders of the Giant Lords, which are some nice, straightforward strength and critical strike rating DPS shoulders, perfect for Death Knight DPS. The Stalactite Chopper is also a pretty solid choice for a dual wielded main hand, though it is marred by some armor penetration.
While the Mages of Dalaran have accepted Death Knights on their streets, they, unfortunately, don't seem to stock much for us in the way of awesome magical artifacts. Still, if you're a Death Knight tank and you have a bit of spare time, you might consider getting exalted anyway, as the Fireproven Gauntlets are pretty much tailor made for Death Knight tanking, with lots of strength and defense, as well as some dodge rating for making Bone Shield last a little a bit longer.
The Frenzyheart and the Oracles
So I actually already told you about one reason to go Oracle earlier today. Seriously, that egg is awesome. But if pets and mounts aren't your bag, there's plenty of other reasons.
At Revered, you'll get your choice of some level 78 plate shoulders. The Glimmershell Shoulder Protectors are very nice for tanks (though you may want to make sure you're defense capped first), and the Gold Star Spaulders are awesome for DPS. Both have plenty of the stats a Death Knights need, and none of the ones we don't. At exalted, the Oracle Talisman of Ablution (which we covered in Phat Loot Phriday) acts both as a nice chunk of critical strike rating and a sort of mini-Butchery proc. At the least, that's good for keeping Horn of Winter up.
I'm not sure why you'd insist on repping with the Wolvar. Maybe you like jerks. Maybe you're an achievement hound. Maybe you're hoping that Disgusting Jar eventually spits out a slime pet or something. I won't judge. I'll just warn you that they don't offer much for Death Knights. The Giant-Sized Gauntlets at revered admittedly work rather well for Death Knight tanks, but their exalted trinket has haste and a frenzy on kill proc, both of which really don't match what the Oracle talisman offers for Death Knights.
Making your Choice
As you can see, every faction does have at least one reason (even if, in some cases, only one) to grind. Choosing which one to grind may, in the end, come down to personal preference. Myself, if I was pressed for time and choosing, I'd probably focus on the Kal'uak for the nice leveling goodies, then the Wyrmrest Accord for the nice outlay of tanking gear, then the Argent Crusade for the nice Revered Mace (And yes, Death Knights can use maces, we just have to train them at a weapons master). Whatever you choose, good luck with your grind, and we'll see you next week. Glacier.