OGRE
Ogres need no introduction and are a clear favorite for Horde. To this day it is unclear why Ogres were not an original part of the Horde when WoW launched in 2004; maybe it was because of Orcs filling the 'brutish warrior' archetype, or maybe it was because of Tauren, since they are a large and powerful race. But Tauren could not be further from Ogres, and Orcs, the other Draenor race, while similar in heritage and personality, are much more refined thanks to Thralls leadership. All things considered, Orcs really are the "Humans" of the Horde, whereas Ogres are the true brutes.
Ogres embody everything the Horde is, maybe even more than the Orcs themselves. They are monstrously powerful, gifted with a savage cunning, and they fully embrace the shamanistic elements. While these Ogre shock troops make the most powerful soldiers, the two-headed variety are more than capable of becoming sorcerers for the Horde. These creatures rival the High Elves of the Alliance in magical prowess, while also producing some of Azeroths most wicked Warlocks.
Turtle WoW is in the unique position of offering the most 'classic' experience that exists for World of Warcraft, and because of that, Turtle WoW is also able to offer the truest "Classic+" experience. Ogres are the perfect fit and perfect culmination of this mindset, along with Goblins, to bring The Horde back to what it was in Warcraft 2 and Warcraft 3; a true home for the most shamanistic and beastly races in Warcraft lore. Ogre questlines, starting areas, and lore, are already baked into what the Horde is and there is so much potential for new level 1-10 questing, exploring forgotten Vanilla Ogre lore, and diving into what makes Ogres such an awesome race. Not to mention, there is much potential with Ogres and Orcs if Turtle WoW ever sets its sights on properly introducing Draenor if or when we go Beyond the Dark Portal (and not what TBC did with space ships and crystals...)
Some other considerations:
Ogres could be sized around Tauren, but slightly larger overall. Two-Headed Ogres do not necessarily need two helmets. One head may have a horn, one may not, which can use the helm. Most gear already fits on them with little to no adjustments, and they already have unique animations, dances, and noises.
Ogres would be the most versatile when it comes to classes on The Horde, as they have several examples of each class, including Rogues (no Paladin or Druid of course). While Two-Headed ogres are traditionally the spellcasters, there are plenty of single headed Mages as well in Warcraft lore, so Two-Heads could be a 'feature' choice.
Their racials have plenty of potential as well; but for starters
Demoralize, send nearby opponents running
Base Defense Increased/Resistant to Damage
Skill with Maces increased (Clobberin time)
Ultimately, I hope you'll agree that Ogres belong on the Horde; indeed, they already are part of the Horde in several locations within Classic World of Warcraft and Warcraft 2 and Warcraft 3 lore.
HALF-ELF or Half-Quel'dorei
Perhaps one of the more mysterious classic races that nonetheless existed in the lore if you knew where to look; Half-Elves combine two of the most key Alliance races. The Half-Elves of Azeroth are Half-Human, Half-High Elf and seem to resemble humans more so than Elves. In WoW, Kalcegos' non-dragon form is that of a Half-Elf. High Elves and Humans are staple races of the Alliance, and have always fought side by side in the Alliance/Horde faction war. As far back as Warcraft 2, Elven Rangers were incredibly powerful allies to humankind. Suffice to say, at some point over the years, High Elves and Humans got pretty close. Throughout the years, up to Vanilla World of Warcraft, so many small hints were dropped throughout the lore about the existence of this hidden race, including via various NPC dialogue in quests and subtle hints in books and stories published by Blizzard.
In Warcraft 3, "Rangers" were originally meant to be a hero unit of the Human Alliance, but were eventually cancelled. They were described as such:
Outside of making an argument for Half-Elves from a lore standpoint, because there is plenty of lore and so many seeds to start with for a Half-Elf questline and settlements within the world, it is said that Half-Elves hold great potential in their bloodline, and could have so many different creative ideas for mechanics for their racials and how they come to take their place in the Alliance.These fearless Half-Elven women are masters of survival and wilderness exploration. Trained to hunt down renegade Orcs and Trolls in the wildlands of both Azeroth and Lordaeron, the Rangers are a force to be reckoned with. Being Half-Elven, the Rangers are often avoided by members of the High Elven stock. However, these crafty females make their home in the wilds and seldom feel the need for the distractions of camaraderie. Rangers are expert marksmen with the longbow and carry specially weighted bows and magically enhanced arrows.
There are so many ideas for races and combinations in the Alliance, but Half-Elves are the one that truly fit the lore and make sense from a Classic+ standpoint. Turtle WoW has already made the right choice in giving High Elves to the Alliance, where they always belonged, as well as Goblins to the Horde. The next step is to explore the deeper lore between Humans, and High Elves, and one way to do it is with Half-Elves.
Some other considerations:
Half-Elves could be sized around Humans, but slightly larger overall. They have the unique position of being able to mix the Human and High Elf models or textures in ne ways. If we look at Kalcegos' model, which is a human with a unique Half-Elf head, all gear already fits on them with no adjustments, and they already have unique animations, dances, voice acting, and noises. Any number of options are available, including mixing the old Blood Elf models from Vanilla (which were themselves Night Elf with different heads) and human models.
Half-Elves would easily be the most versatile when it comes to classes on The Alliance, as they are a fusion of High Elf and Human, and would make excellent Paladins.
Their racials have plenty of potential as well; but for starters we could mix Human and High Elf, or give Half-Elves a truly unique or powerful racial that speaks to their lore about mixing powerful bloodlines.
Summarizing Ogre and Half-Elf
Ultimately, I hope you'll see that both Ogres and Half-Elves belong on The Horde and The Alliance. I hope you'll look them up and come up with your own ideas for them; in the end, I think you will agree that both already exist in the lore and are already true parts of each faction. Ogres, a true mascot for The Horde, and Half-Elves, embodying everything the Alliance stands for by literally being Human and High Elf; I think these two races are exactly what Turtle WoW needs to continue to forge the greatest Vanilla WoW and "Classic+" experience that exists, and to expand upon the lore that Blizzard so meticulously crafted from Warcraft 2, 3, and Vanilla WoW, but for some reason abandoned with future expansions.
Thanks for reading!