Ashtongue Deathsworn (H)
Unless and until you begin to raid, then don't bet on getting these faction recipes. Still, once you are able to begin the grind, you will get two plans at friendly, and the other two at honored, which is relatively painless.
The items focus on stamina and shadow resistance. At friendly, you'll be able to purchase [Plans: Shadesteel Bracers] and [Plans: Shadesteel Girdle]. At honored, pick up [Plans: Shadesteel Greaves] and [Plans: Shadesteel Sabots].
While these have limited use outside of very specific fights, they are bind on equip and can be sold or given away.
Violet Eye (R)
Although this is another raiding faction, Karazhan is an entry-level raid, awards ample amounts of badges, is easier to get a spot in, and the reputation grind goes quickly.
Like the Ashtongue Deathsworn patterns, the pieces are stamina and resistance gear. These pieces are frost resistance, and as an added bonus, have some defense rating as well.
At honored, you'll be able to purchase [Plans: Iceguard Breastplate] and [Plans: Iceguard Helm], both of which carry defense rating. Once revered, you'll be able to purchase [Plans: Iceguard Leggings] which do not carry defense rating, but are still great for boss fights where extra stamina and frost resistance is required.
Cenarion Expedition (E)
The plans available from the Cenarion druids are more interesting than the raiding patterns, although the pseudo-set (Wildguard) looks suspiciously like the Violet Eye patterns, with nature resistance in place of frost.
At honored you will have the option to purchase three white quality patterns. Fortunately, honored is easy to reach just by questing in Zangarmarsh and handing in [Unidentified Plant Parts]. [Plans: Adamantite Sharpening Stone] and [Plans: Adamantite Weightstone] are nice upgrades to the trainer-provided weapon stones. They're also not terrifically expensive to make, compared to many other blacksmithing items. [Plans: Greater Rune of Warding] is also a great temporary self-enchant, requiring a whopping 0 materials to cast.
At revered you begin to have access to the Wildguard "set." You'll have the option to purchase [Plans: Wildguard Helm] and [Plans: Wildguard Leggings]. At exalted, you'll be able to purchase [Plans: Wildguard Breastplate]. Because these epics are, like the raiding items, bind on equip, you might be able to sell them to raiders without blacksmithing.
Honor Hold or Thrallmar (E)
While you don't get much from these Hellfire Peninsula factions, you do get a new shield spike. [Plans: Felsteel Shield Spike] is great for threat generation or soloing if you do so with a shield, and so count on running an awful lot of Shattered Halls at 70. Try not to leave the Peninsula until you've finished all quests, and definitely do the Hellfire Citadel dungeon quests.
Unfortunately, Ramparts and Blood Furnace stop awarding experience once you've cracked friendly (5999/6000). It might be wise to run these until that time, before pursuing quests in the area.
To boost your reputation gains, repeat the quest Hellfire Fortifications. You'll find this in the main outpost, and with the tokens you acquire, you'll be able to purchase multiple favors like [Thrallmar Favor], which work wonders in dungeons. Not only will you level faster, but your reputation gained from the kills is increased by a quarter!
Aldor or Scryers (E)
Choosing between these two Shattrath City factions will likely come down to matters that have nothing to do with the blacksmithing plans they offer. This is because the sets available are bind on equip, and thus you can acquire the gear from the Scryers even if you are Aldor, and vice versa.
Similar to the raiding gear and the Cenarion pieces, these are resistance gear. The Aldor offer the Flamebane set, offering stamina, fire resistance, sockets, and socket bonuses, and a set bonus of +20 parry rating at 3 pieces equipped.
At friendly, you can purchase the [Plans: Flamebane Bracers], and at honored, [Plans: Flamebane Gloves]. Once revered, you can snag [Plans: Flamebane Breastplate], and when you reach exalted, which can be expensive, [Plans: Flamebane Helm]. Fortunately, you could equip the three pieces and get the set bonus without having to reach exalted.
The Scryers offer the Enchanted Adamantite set, which contains arcane resistance instead of fire. At friendly, purchase [Plans: Enchanted Adamantite Belt], at honored, grab the [Plans: Enchanted Adamantite Boots]. Once revered, buy [Plans: Enchanted Adamantite Breastplate], and you'll be able to have the same set bonus as the Aldor set. Once exalted, which is likewise expensive, purchase [Plans: Enchanted Adamantite Leggings].