Honestly? I'd wait for 7.3 to drop.
I keep leaving WoW for a month or two at a time and then returning, only to find out there is still nothing much to do (I don't raid, only run low-ish (~10) M+ with friends couple times a week on few characters and find current PvP more atrocious than Hunter Class Design).
You said you were gone 5 months, which means you'd have the whole of Broken Chore opened to you - 12 quests, filled with finding chests, killing demons, killing some more demons and killing demons to loot marks from them. New dungeon, Cathedral of Eternal Night, and a new raid - Tomb of Sargeras (possibly, Nighthold, too, if you didn't run it). With the currentl ilvls the Broken Chore's Mage Towers to unlock your Challenge Appearances are becoming much easier, too.
On the good side: You can level your Artifact Knowledge to 40 over couple of days if you have enough resources. Then you can buy a book and send them to alts to get them to 40 instantly, which would ramp up their AP gains greatly, leading you to unlock Class Mounts and Class-specific battle pets, toys, etc. at a much faster rate.
BM Hunters got a nice change in terms of getting a 2nd charge of Dire Beast / Frenzy baseline and increased range on KC / DB / DF and Hati using Rush when your pet does. MM has become less dependent on Vulnerable, too. SV got patted on the shoulder.
Couple new Spirit Beasts - Gon and the Lost Spectral Gryphon and the whole new family of Feathermanes, too, with some pretty neat and unique pets.
There are neato Pet Battle Dungeons, if you're into it, although they get sorta boring after couple times, but you still will have to run them to get all the pets
EDIT: Oh, there is also The Deaths of Chromie scenario. It gives a couple of pets (bronze proto-drake and bronze drake), the title of Timelord and a
transmog set (updated version of the
Mistshroudfrom TBC). It is fun, but you really can get everything out of it in half a dozen runs, and then there is no reason to return.