Hello! I've been playing this game for well over 7 years, and recently I've been experiencing a ridiculous amount of indecision in finding the right class for me. Hopefully, I can describe some things about me and my personality and gameplay preferences and your collective knowledge can help me find some identity in a class.
I'll split this into 3 things: classes I've tried (and what I enjoyed about them), some self-defined personality traits, and some elements of gameplay I enjoy.
Since my raiding career has started, I've mained a couple classes. I started with a Resto druid in 3.2, where I really enjoyed the druid's ability to heal on the move. Starting in Cata, I led a team of my friends into normal 10mans as a Resto shaman. The uniqueness of the shaman felt nice, where it was a combo of HoT and casted heals. After my friends and I fell out, I played a rogue for 4.2-5.0, and I really found a lot of fun and felt a sense of identity playing a single-role class. I could enjoy PvE and some PvP without feeling too diverse. After a brief haitus from WoW, I came back and rolled (ba-dum-tss) with a monk. I leveled as Mistweaving/WW, but at 90, I quikcly got into brewmaster. I really enjoyed the unpopular-ness to the Brewmaster, and their unique playstyle with micromanagement. I've played some alts, such as a Prot warrior, Enhance Shaman, and Feral/Guardian druid. I enjoy elements of all of these, with mostly the aspect of having some defensive bruiser-esque abilities used by a melee fighter.
Personality-wise, I find myself to often as somewhat anti-social, quite dull outlook on the world. I can be really grumpy, but deep down I see myself as the silent guardian. I feel inclined to make sacrifices for others, and I would rather I struggle with something than a friend of mine. This is what pushed me towards tanking. I also have many traits of a strong leader, and I felt tanking was the easiest role to lead people with. While I may not be especially skilled at any given talent, my ability to communicate and assess situations and quickly make decisions made tanking a natural place for me.
Some last few things I've noticed: I'm not a fan of ranged combat (kiting doesn't appeal to me), and healing isn't my favorite thing to do (but I'm not completely against it). I really find enjoyment in a classes' uniqueness, the uncommon, not-so-popular, anti-flavor of the month aspect of a class. I would like to reunite some members of my old team and raid again in the near future. I like to be very self-sufficient, and have the ability to do things on my own is also pretty appealing. I like to have one character and play that one almost exclusively (not a huge fan of alts).
I'm not really sure what other information to add, I don't want this post to seem way too TL;DR. If you would like any more information, please, ask questions! I appreciate your responses in advance; your advice will help me keep interest in this game I've known for so long!