do yourself a big favor and take a break from playing WoW, and read the books. I have been playing since vanilla as well and was in the exact same boat as you. Did LFR Deathwing maybe twice and reflected on the game and was like "...fuck. this game blows now" Boy was I wrong
I have such an amazing newfound love for the game and really enjoyed taking my time leveling a draenei(have been Horde for 6.5years), and enthralling myself in the lore. It makes you actually care about the game. Almost as much as the feeling that you had when you first started playing WoW.
I have always been an avid PvP'r, and now that is so much more fun because I'm playing to have fun and enjoyment, NOT for KB's and to qq at afk'rs.
Make the game yours, and enjoy yourself. Why pay for any other reason?
P.S., IMO, read the books chronologically in Warcraft time. Rise of the Horde --> The Last Guardian for the first two
COULD NOT AGREE MORE!!!! its such an amazing reset after playing for 7+years