Well the faction, as far as I know matters little but the class varies quite a lot, oh and if you're a shadow priest you have a pleasant suprise awaiting you in the Emerald Nightmare raid.
Pffff...I had the premonition they might to mirror quests for all zones bar Broken Shore.
I have a Troll Shaman ( duh )

))) and a Night Elf Warrior.
I think Varok would have been a better choice but what can you do, she's the WarChief.
For me, the lore appeal went down with Thrall removal from Warchiefhood, he was perceived as the Horde hero, him being pushed as a neutral hero was very bitter.
Thrall was, indeed, the only high profile Horde hero who could, in theory, serve as a neutral Hero but my doing that it caused the Horde to lose it`s only very high profile hero.
In Vanilla, TBC and WotLK the Horde were only supporting characters in a world run by neutral heros from the Alliance races fighting against former Alliance members.
I guess that with Cataclysm Blizzard wanted to level the plainfield but it turned out a disaster.
In Vanilla, TBC and WotLK the Horde were some desperate races that clung together. Bar Orgrimmar and a few other Orc settlements the Horde were living in shacks while the Alliance had huge awesome settlements with proper castles and such.
The addition of the Blood Elves in TBC and the Kor`kron, with both awesome new armour and architecture, in WotLK worked in changing the Horde`s image as a bunch of primitives but it went down the hill with Cataclysm and especially MoP.
For me personally it was very bitter, the Horde reconfirmed the bias of bloody brutes bent on conquest and the Alliance reconfirmed the bias of knights in shining armour.
They had the perfect setting with MoP, they could have very well pushed Varian down Garrosh`s path and having the Horde and Alliance rebels siege Stormwind.
It would have been a much needed PR boost to the Horde and some much needed bad PR for the Alliance, confirming that both faction are grey.
This way the Horde`s redemption for what happened in the Second War would have been over but we end up needing the Horde another redemption without finishing the first one.
It`s very sour.
As for who the Horde could have had as a neutral hero, look no further that Etrigg, he could have been a perfect second-in-command to Tirion in the Argent Crusade.
As for a proper neutral faction with majoritary Horde members we could have had the Earthen Ring.