I got the druid class this time (the 9th that reached the end-game) because of the very reason that created this double dilemma, I'm unsure of what to play in this game. I had started on a ranged in TBC but it never reached end game, silly me back then thought that it'd be superior to roll a melee since I had been ganged once or twice in a pvp server in world, but then soon realized that everyone thought melees are useless in anything but arena (in overall), so I moved on to the other end and become a tank, but that wasn't that amazing, since while I was good enough, I always felt a bit off about it, it was a bit easy being considered on anything (tanks are rare) but at the end of the day tanks are 90% management and 10% numbers and I'm more of a number crunching type of guy. So I went back to being a mage for cata and while I was successful for a long time, I also rolled various alts at the same time in tanking and healing roles (healing, that I had never played until then, a very interesting endeavor).
Now that I came back for a while, I feel like I burned the ranged role a bit, I got too used to their single target rotations of the class I played and frankly I got a bit bored of bliz's attempts to make the role harder than it is (e.g. ads that spawn 40 yards afar and you must switch with mouseover macros and other convoluted frustrating things you have to do in performance raiding). But at the end of the day, melees are still considered suboptimal, in January 2014 people still see the roles appoximately similar to TBC, tanks are few, healers more, ranged more favorable and melees the outcasts.
But the thing is, I found the cat more fun than the other specs in the beginning, and I had to play a melee for so many years it was interesting (and frankly I find the balance spec completely mechanical and clunky, especially compared to the big variety of full ranged 3-spec class), but I also find the healing spec slightly more interesting than some other roles in the game, and the tank spec, while I could maybe prefer it more than balance, tanking in general in this game is a double edged sword, on one hand you can be instantly considered for almost anything your gear can handle, but on the other the very nature of the role itself is very management-driven and too little personal-performance driven so it becomes a bit "people/raid management" overdose sometimes.
I am like you somewhat in not knowing what I feel like playing much, I played a shaman and warrior in vanilla, only raided with warrior as an off tank.
Then in BC I switched to Warlock and raided as affliction which I thought was fun, I really enjoyed DoT management and banish on demons in certain fights or fear.
For WotLK my guild needed a healer so I went back to Shaman and healed through wrath, was fun until we had stuff on farm then it was boring.
I didn't play Cata at all just for am onth after release I think.
For MoP Ive been raiding as a DK frost with tanking on heroic fights that we need to 3 tank. I hate it DK is so boring now for me
Anyway Im switching to feral, which is a DoT management like my warlock was, I tried resto shaman (i hate it in mop) boomkin (doesnt feel mobile enough) and mage which also is to much standing around waiting for a castbar to complete.
So anyway I would try feral if you like managing buffs and debuffs, I've heard Warlock is very fun and each spec is viable and fun they have a lot of raid utility also so that might be something to try out if you dont like feral or are worried about being melee.