I just finished leveling a hunter from lvl 10-80 in 7 days 22 hours played, grinding with Botanist's Pangaea profile "pack".
Only issues i experienced were about lvl 35'ish, on the border to a thousand needles. It seems to "sit" and go afk on a part there, due to it being on a phased zone line - That causes it to basically just sit there, untill you move it

And ofc. the last issue; Warsong hold, it simply does not work atm. lvl 68-70.
I recommend using: [Grinding] Indu'le Village + Snowfall Glade Dragonblight - if you're horde, just edit the file to lvl 68 instead of 70. It works perfectly, lvl 70-71 mobs. so it goes fast

Then simply start up Pangaea once you hit 71, and it's good from there.
Overall 95% AFK'able.
^^^^
The above isn't really fast, Kick's questing used to be faster.
However, the !K questing pack seriously needs to be edited

way to many stucks etc. for it to be afkable.
And i'd rather have it take 2 more days, and be 95% afkable, than 5% afkable ^^
To answer the question;
Questing is best, but doesn't really work that great atm.
Grinding is easy and more stable.
Raf and using a *5 dungeon team is probably the fastest
But try out a few things and get some experience on it, that's the only way forward.