patch 5.4 is said to be the last patch in mist of pandaria, so, maybe it is time for us to make a conclusion about what is the most welcome class in mop. we have got data about the number of full-level classes. by comparing the number of classes that upgrade to 90 level in mop since cataclysm, you can get the answers very easily.
the orange bar represents the number of players who have reached level 85 with certain class in cataclysm. the blue bar represents the number of players who have leveled certain class to 90 levels in mop. it is easy to see that the number of death knight increased a lot. then it is the hunter and warlock. the number of players who play as druid, priest, rogue and warrior almost stays the same. mage is the only class whose numbers has decreased a lot.
here is another chart for you which shows the characters reached level 90 from level 85 since the release of mop. we can see from these two charts that the characters of each class are basically on the same level. maybe rogue is the weakest for now. but who knows whether this class will become stronger in the later editions of world of warcraft. if you just want to start your journey or you want to upgrade a second class, we suggest you hunter, warlock or the druid.