Horde: do the quest in the west end of hillsbrad to be a questgiver

Peacebloom vs Ghouls quest chain in hillsbrad (any faction)

quest chain from the human paladin by the hot springs in un'goro

various quests for horde in azshara, doing whole zone is recommended, same goes for stonetalon for both factions

whole of redridge mountains for alliance

the Schnottz chain in uldum

goblin starting zone for same reasons as previously mentioned worgen starting zone, pretty much

ring of blood event in twilight highlands (crucible of carnage)

jousting quests in hyjal

kill a Whale Shark in Vashj'Ir

Battlemaiden chains in vashj'ir