Druid - the shapeshifting thing always annoyed me.
Shaman - have one at 78 lvl, took me an eternity to get it to this lvl, really struggling to play it, so weak and meh…would boost and be done with it but it is dark iron and I need it for achievement.
Monk - never tried and won’t because I dislike the class lore and philosophy that goes with it.
DH - nothing personal but for me this class looks like it’s for little kids 
Shaman, Priest and Mage.
I think that’s one of the charms of being a rogue tbh.
Any rogue can hit their head on the keyboard and do " fine dps "
But it takes an extreme amount of skill to do giga dps.
While I don’t play my rogue atm, but I can gauge between my friend that plays with me and other rogues and the difference is often very huge.
It’s pretty hard to find a rogue that does a big amount of dps, let along find a rogue that does big dps and actually actively controls mobs and minimizes damage taken.
As much as I would like to call the current rogue design trash, I can’t deny it has a very big skill gap.
Чеба , most fun class to play.
If it’s not a warrior, I don’t play it.
I play all classes, but the one i have a hard time with and can’t get the hang of are Monks. All specs, just not my cup of tea i guess 
Most Melee classes. I’m a spell slinger / healer and for some reason I cant really grasp melee combat. The only exceptions is my Paladin tank and my Feral Druid. But I tried and totally sucked at Rogue, Warrior, DK, Monk and DH 
Classes I play for their lore, cool trans mog sets and Hall in Legion just because of how utterly awesome they really are and how abilities are as brutal visually as they are physically:
WARRIORS, WARRIORS AND MORE WARRIORS.
And just slightly paladin
I have a Pala at 102. I don’t think I will ever consider playing it again even as an alt. I’ve had it just for professions but then realised I would have to plenty of stuff to level professions to the highest level and gave it up completely. It’ only a bank storage.
DPS range and casters: Hunters, Warlocks, S Priests, Ele Shamans, Boomkins and Mages.
I find them too easy mode and I prefer a little bit of a challenge while you try not to tunnel-vision or fall asleep healing others.
Warrior: its my least played class to me its just a boring class
Demon Hunter: feels like a single trick pony only thing that i found fun in it was gliding.
Druid: I used to love druids got two of them at 70 in tbc and 2 in wotlk but after they changed the gameplay of moonkin in cataclysm i just lost interest.
Warlock: I love the class the lore and tier sets might be the best around every class. Only if the gameplay was on par with the rest. The class feels slow and boring to play and without any speed boosts except the burning rush the gameplay is just painful.
Paladin: I just don’t like the knight in shiny armor stuff at all.
Shaman: Used to like the class but i got bored blizzards inability to understand the class and the constant cycle of either being a Zeus level of power house or just a toilet of other classes to crap on.
Monk: Getting rid of fistweaving and stances killed the class for me.
Demon Hunters
Death Knights
Monks
Reasons? I just dont like them. I have a thing with new classes I guess. 
Sadly i do not enjoy playing many alts these days, especially since essences came out I just cant be bothered. Only really played druid, monk and outlaw rogue this xpac after leveling it to 120.
I have everything except warrior and wlock at 120 and those 2 are 110.
Obviously druid is my main and i absolutely adore them.
As for the ones i really dont like lets see
Warrior on top of the list 100%, any spec.
I have played with all classes at some point.
I do, however, have some totally abandoned:
Mage
Warlock
Rogue (this one was the first class I ever played and I think I still have some PTSD from it lmao).
Overall, I think I seem to have a problem with just dps classes. I play mostly healers and to some extent tanks.
I really don’t like palas but since I had to play an ally to get the rep for Kul Tirans I made one, so I can try one.
Damn, is a pala boring.
Odd thing is that while druid is my favorite class ever since launch. Prior Kul Tiran project, out of my full L110 army in Legion - that was at end 36-38 characters, only 1 … ONE was druid. Now I have 2.
My 1st live character was a druid and she has always special spot in my heart. She just represent something about and for me. My past, my memories. In and out of game. 
So druids are the best ! And yet I have least of them in my army. My least favourite class is paladin, and even those I have like 4. 2 Blood elves, dwarf and lighrforged, and other class I dont sync well is warrior and those I have L120 like 3 night elves and 1 void elf.
Most of my characters are death knights. i like death knights. But BfA leveling been a bit annoying at horde so my horde dks are 110. Most of them.
Rogue.
I just cannot find it enjoyable to play in any form whatsoever. the only reason I made one was to get the Dragon Soul legendary daggers, soon as I got them never looked at it again.
Warlocks; not interested in fel, domination, demons, or the visuals.
Death knights; not into undeath.
Demon hunters; they look ridiculous outside of Legion content and are basically for people who wanted the mobility of a monk without the skill cap.
Rogues… I have never reached max level with a rogue, but I sort of want to. I like the sneaky sneaky concept and the picking and choosing of fights and the never getting tied up in things you didn’t want to get involved with. However, a druid is arguably better at all of these things, plus higher mobility, plus it can take literally any party role.
But since maining a monk, it’s hard to love anything else. Druid is a close second and situationally better (e.g. open world farming or when I wish I could stealth), but nothing else comes close for me, and I’m going to have a really hard time with anything that can neither tank nor heal.
Dh - just no
Druid - to many things to deal with
Mage / warlock / priest - i dont like cloth
Monk - allready got a drinking problem
Dk - to slow moving for me
Paladin - wife talks enough about religion as it is
All others are ok, pref prot war,outlaw rogue and sv hunter.
Rogue - too squishy, convoluted gameplay, I prefer casters
Kitty druid - Rogues Mark 2. Actually worse. Much worse.
I only play dps, so these are the two I hate the most.
Not a great fan of warriors either, but they’re kinda ok. There are worse classes.
Like Kitty Druids.