Why Post Ore?
People may feel that since many of the professions can be leveled up via materials from Draenor there is no longer a demand for lower level ore. In my experience I have found the demand for ore has decreased, but the price has often increased for some ore that people just don't wanna go farm.
It is best to check your AH daily to insure that you know when some ore increases in value, this will significantly help you figure out which type of ore you should be farming. I also encourage people to farm different types of ore because if they do not sell fast you don't want to be stuck with only one type of ore. The information I found was used on a popular website and is just compressed or changed slightly to make a few changes to the gathering paths.
For functionality if your character is level 90 or above and not a mage I suggest placing your hearthstone at the shrine in Pandaria. This will allow you to use many of the portals for quick travel between locations. Further, I suggest that you activate all of your portals in your capital city to make travel easier.
Copper Ore
Durotar-Horde
While there are a few maps that have copper ore this map is the closest and easiest one for the horde player.
Darkshore-Alliance
This map is closest to Darnassus which is nice for the mage gatherer or a short flight from Hyjal.
Tin Ore
Hillsbrad Foothills-Horde
This map is is best for farming tin ore on a horde toon due to its proximity to the undercity.
Northern Stranglethorn Vale-Alliance
Only a short flight from Stormwind, this map is perfect for an alliance character wishing to farm tin ore fast.
Iron Ore
Western Plaguelands
I find that this is the best map for both factions to farm iron ore.
Mithril Ore
Burning Stepps
This map is a short distance from Stormwind for alliance players, and only a short flight from Stonard for horde players.
Felwood
Because this map is close to Hyjal it is accessible by both factions.
Thorium Ore
Un'Goro Creater
By far the best map for farming thorium ore. Forget all other maps! This map is also only slightly above Uldum, so if you have the portal to Uldum you can get there fast.
Fel Iron Ore
Hellfire Penninsula
Probably one of the most annoying ore to farm, which is why it is usually more expensive. but the generally best places to farm is located in this map.
Adamantite Ore
Nagrand-Outlands
This ore is harder to farm than others due to the fact that the zones which have it are also shared with fel iron ore nodes. In my experience Nagrand happens to be the best place to farm this type of ore.
Cobalt Ore
Borean Tundra
I find that Borean Tundra is the better place to farm Cobalt ore. While there are other maps to farm this no map is enjoyable. I suggest putting on a movie or television show while doing this because its not exciting and does take considerable time.
Saronite Ore
Wintergrasp
I find that Wintergrasp is the best place to farm Saronite Ore many of the nodes are Rich Saronite Ore and some nodes are Titanium Ore, which is very valuable
Obsidium Ore
Hyjal
Elementium Ore
Uldum
This map is easy to get to via the portal in the capital city. This map also has a fair number of the rare Pyrium Ore nodes.
Ghost Iron Ore
Valley of the Four Winds
This map is the best map for finding Ghost Iron Ore. The portion in red is added to indicate that you should not follow this route every pass of the map