Alright, may as well try it out. At the moment I have an 0/17/54 Unholy DK, but I'm willing to roll a Warlock (my old main) or Mage.
Curiously... what don't you like about horde?
Long story. If you tl;dr, I'm a lore nerd and don't like the Horde with the almost sole exception of Thrall. Just about everything progressive in Azeroth has been done by the Alliance side, with the exception of listening to Medivh and fleeing to Kalimdor, but then again, Jaina did that too.
I came to WoW long after the release of WotLK, after playing the Warcraft III 1v1 ladder competitively since release, peaking at around rank 600 in US East, which honestly, isn't that good. Since I played Undead, and Undead picks Death Knight as first hero in 3/4 or 4/4 matchups depending on your style, when I heard they were making DKs a playable class in WoW I was excited. So, the first thing I do is roll an Undead Warlock (thinking it would be the closest thing to a Lich. Should have gone Frost Mage instead).
So, I quest all across Azeroth and Outland on my way to Lv. 65 (was originally planning on capping my Warlock before rolling a DK) and, being quite the lore buff after playing the Warcraft III: Reign of Chaos and Frozen Throne campaigns all the way through on Normal and Hard, I came to the following conclusions about the Horde: They're lame.
The Alliance has all the epic cities: Stormwind, Ironforge, Darnassus, and my favorite, Dalaran. To a lesser extent, Shattrath and the Exodar. The Horde has Orgrimmar (an ugly clusterfuck), and the Undercity... which is the ruins of an Alliance city.
In terms of races, the Humans are a bit dickish, but the Dwarves have a great focus on creating things (metallurgy and stonework) and discovering history (the Explorer's League). Gnomish Engineering is awesome, and the Gnomes are basically the most technically advanced guys on the planet. The Night Elves spawned the most powerful mortal mage born on Azeroth (Azshara), and Tyrande / Malfurion are the best racial leaders in the game, having been instrumental in fighting off the Burning Legion twice over 10,000 years. The Draenei are space goats with awesome face tentacles. Enough said. Oh, and Archimonde was only killed by the combined forces of nearly all Azeroth, after leveling Dalaran with a single spell. And he's still not as strong as Kil'Jaeden, who is probably the strongest non-Titan immortal mage, but who barely ever needs to break out the magic. You know the Wrath of the Lich King? Yeah, he created the Lich King.
The Horde races are all basically nomadic and/or tribal, except for the Forsaken, who want to kill every other living thing on Azeroth. Good job, guys. The Blood Elves are the most advanced, having built an epic city and helped defend Azeroth in the 2nd and 3rd wars before going on a revenge trip fueled in part by their heroin, er, magic addiction.