Not to be mean or rude or anything but I'm kind of annoyed of people asking where to level or something (I'm not calling out names ^^) but they might be new to the game so that kind of counts . One day during the 2x XP event that happened somewhat in March/April, I leveled up quite fast (aside from the 2x XP event) but it was way faster than I thought. I got to level 200 in less than a week so I get to create another one. Anyways, I have came up to my conclusion that this is the place where to level up (based on my opinion) the fastest. If you have other places to level, that is fine with me. For me, I have good gear with (not to brag) a +9 Short Sword + cleric buffs so the leveling place results might be different than when you try it.
Level 1 - 6: Adventurer's Plains - Jellybeans/Choropies/Flanaes (then get your identification)
Level 7 - 10: Valley of Luxem Tower - Pumpkins/Elder Pumpkins/Pomics/Needle Honeybees (then go to junon)
Level 11 - ~28: Canyon City of Zant - Woopies/Woopie Chefs/Woopie Glutton/Hornets
Level 29 - 40: City of Junon Polis - Moldies/Grunters (the ones on Junon)
Level 41 - 55: Forest of Wisdom - Clowns/Fighter Clowns (party + aoe DEFINITELY recommended)
Level 56 - 60: Kenji Beach - Doongas/Elder Doongas
Level 61 - 75: Kenji Beach - Krawfies (all kinds) [lurer + aoe + cleric DEFINITELY recommended]
Level 76 - 85: Gorge of Silence - All kinds of Golems (lurer + aoe + cleric recommended)
Level 86 - 100: Goblin Cave (B3) - Goblins [duhhhh] (sacrificer + aoe + clericS + full party DEFINITELY recommended)
Level 101 - 110: Arumic Valley (Southwest) - Golden Yetis (cleric + aoe + lurer recommended)
Level 111 - 149: Oblivion Temple (B2) - Mammies/Mummies (full party + lurer + aoe + clericS recommended)
Level 150- 162: Oblivion Temple (B3) - Golems (full party + lurer + aoe + clericS recommended)
Level 163 - 200: Sikuku Underground Prison - Sikuku Prisoners (full party + long ranged + clericS + aoeRS DEFINITELY recommended)
Level 201 - 210: Sikuku Ruins - Devil Pest Arachnids (lots of spawn place spots there - good luck)
Level 211 - 219: The Wasteland (BONUS FARMING INVOLVED) - (forgot name) [boss that spawns most epics] (Full party + cleric recommended){PVP champs/Katar Raiders/PVP mage/ 2 clerics RECOMMENDED in party}
This might not accurately work especially the Level 211 - 219 one because most people dont want to take the Orlo quest or too lazy to do it because.. and let me tell you... it sucks and long and sucks and painful.... If you have a pretty reasonable gear and you follow my guide (with a medal/happy hour) you will be level 200+ in no time... like i said, this is not 100% accurate so dont blame me for expecting too much for me xD
HAPPY LEVELINGS!