60 Exalted Reputations

Final Update As of 7.0 release this achievement will be superseded by 70 Exalted Reputations, at long last! As someone else on that page took this idea and expanded on it, there's little point in having two competing lists, so I will stop maintaining mine, and will mark this post out of date soon after 7.0 launches. Thanks for all the positive feedback over the last few years; I hope this post has been useful :-)

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Of the currently obtainable factions which actually count, there are now 84 possible by any one character, 86 if you happened to get Shen'dralar and Zandalar done before the Cataclysm. Taking the 150 factions currently listed in Wowhead and breaking them down we get the following (warning: wall of text!):

(* = New in Warlords of Draenor)

Alliance-only:
Alliance Vanguard
Baradin's Wardens
*Council of Exarchs
Darnassus
Exodar
Explorers' League
Gilneas
Gnomeregan
*Hand of the Prophet
Honor Hold
Ironforge
Kirin Tor Offensive
Kurenai
Operation Shieldwall
Pearlfin Jinyu
*Sha'tari Defense
Silverwing Sentinels
Stormpike Guard
Stormwind
The Frostborn
The League of Arathor
The Silver Covenant
Tushui Pandaren
Valiance Expedition
Wildhammer Clan
Wintersaber Trainers
*Wrynn's Vanguard

Total: 27

Horde-only:
Bilgewater Cartel
Darkspear Trolls
Dragonmaw Clan
Dominance Offensive
Forest Hozen
Frostwolf Clan
*Frostwolf Orcs
Hellscream's Reach
Horde Expedition
Huojin Pandaren
*Laughing Skull Orcs
Orgrimmar
Silvermoon City
Sunreaver Onslaught
The Defilers
The Hand of Vengeance
The Mag'har
The Sunreavers
The Taunka
Thrallmar
Thunder Bluff
Tranquillien
Undercity
*Vol'jin's Headhunters
*Vol'jin's Spear
Warsong Offensive
Warsong Outriders

Total: 27

Neutral:
*Arakkoa Outcasts
Argent Crusade
Argent Dawn
Ashtongue Deathsworn
Avengers of Hyjal
Bloodsail Buccaneers
Booty Bay
Brood of Nozdormu
Cenarion Circle
Cenarion Expedition
Darkmoon Faire
Emperor Shaohao
Everlook
Gadgetzan
Golden Lotus
Guardians of Hyjal
Guild
Hydraxian Waterlords
Keepers of Time
Kirin Tor
Knights of the Ebon Blade
Lower City
Netherwing
Ogri'la
*Order of the Awakened
Order of the Cloud Serpent
Ramkahen
Ratchet
Ravenholdt
Shado-Pan
Shado-Pan Assault
Sha'tari Skyguard
Shattered Sun Offensive
Sporeggar
*Steamwheedle Preservation Society
The Anglers
The Ashen Verdict
The August Celestials
The Black Prince
The Consortium
The Earthen Ring
The Kalu'ak
The Klaxxi
The Lorewalkers
*The Saberstalkers
The Scale of the Sands
The Sha'tar
The Sons of Hodir
The Tillers
The Violet Eye
The Wyrmrest Accord
Therazane
Thorium Brotherhood
Timbermaw Hold

Total: 54

Mutually Exclusive:
Frenzyheart Tribe/The Oracles
The Aldor/The Scryers

Total: 2 (4)

Cannot reach exalted:
Darkspear Rebellion
Gelkis Clan Centaur
Magram Clan Centaur
Shang Xi's Academy
Syndicate
The Brewmasters

Total: 6

Removed*:
Shen'dralar
Zandalar Tribe

*These still count if you already have them, so older characters count yourselves lucky!

Total: 2

Do not count:
Bizmo's Brawlpub*
Bizmo's Brawlpub (Season 1)*
Brawl'gar Arena*
Brawl'gar Arena (Season 1)*
Chee Chee
Ella
Farmer Fung
Fish Fellreed
Gina Mudclaw
Haohan Mudclaw
Jogu the Drunk
Nat Pagle
Nomi
Old Hillpaw
Sho
Tina Mudclaw

*I assume the two brawling factions do not count

Total: 16

Unsure, suspect do not count/do not exist?:
*Aeda Brightdawn
*Barracks Bodyguards
*Defender Illona
*Delvar Ironfist
*GarInvasion_Breakers
*GarInvasion_IronHorde
*GarInvasion_Ogres
*GarInvasion_Primals
*GarInvasion_ShadowCouncil
*GarInvasion_Shadowmoon
*GarInvasion_ThunderLord
*Leorajh
*Operation: Aardvark
*Shadowmoon Exiles
*Steamwheedle Draenor Expedition
*Talonpriest Ishaal
*Tormmok
*Vivianne

Based on the Tillers NPCs, I do not expect the various bodyguards to count, while the others appear unimplemented

Total: 17

This must be completed on one character, so unfortunately you can't grind different reps on different characters.

Currently on Live the Tillers NPCs no longer count towards this upon becoming best friends. That makes this significantly harder to do.