Fortunately, Heavensward-Dungeons are giving double exp since a few months ago. You can go from 59 to 60 within 3 Gubal-runs.

My only complain is, that the challenge log will not increase the EXP reward with every level up since level 50. I mean, around 80k EXP Bonus is pretty nice with 50, but much worthless with 59. Is there no chance to increase the max until 60?

Doing dungeons/roulette all the time as a DPS can take much longer than as a tank-class.
Levequests can be nice, but its annoying to travel back and forth every 3 levequests.
The new Beast Tribe Quests can help, but you still can do 3 or 6 per day.
Challenge Log stops at Level 50.
Daily Hunts can give you EXP too, but not that much.
And FATEs arent that good at the moment.

I dont expect to have a "Gimme all classes to 60 now"-Button. But it took much more effort and time to get all DoW-Classes to 60 compared to all DoL/DoH-Classes (which took only a few weeks for all).

I wished there would be some kind of potion you can get after you earn a fixed amount of EXP in Level 60 Dungeons. Like doing 10 Level 60 Dungeons with your main class and you got a level-up-potion for your second class. Hell, if I have the option, I would rather buy 5 Level-Up-Potion for 500k Gil or 5 bucks xD But thats unrealistic and would cause more problems. Some people might say: Playing a class to 60 will help to learn the class. But the truth is: There are still many people to grind brainless to 60 and arent still able to play their own class. So thats not a valid argument to me.

So... I m still wondering: What is the most effective/fastest way to level up at the moment? How is it possible to get from 50 to 60 withing 10 hours? O_o