I Took forever trying to decide a main. Literally 3 hard years of trying various races with classes and analyzing damage meters / Play style.
Below was pretty much my findings however many would probably say skill issue, due to being new at every class I tried but thats part of the experince in bringing in new blood imo.
Ranged.
Hunter- Great at PVE, get good at placing traps in PVP or get rekt. only ranged class that seems to be able to move and fight at the same time and only ranged physicle damage class. Easiest rotation to learn for newer players.
Mage- Great in PVE, Get steam rolled by a rogue and generally every melee class in pvp. Doesnt apply this patch due to seemingly infinite blinks. Frost mage does amazing at melting melee due to constant CC thats almost unavoidable if good at blinking away from players.
Warlock- seems to be the second Tankiest cloth class, Does massive dmg but skill cap felt high.
Priest-Before being nerfed the tankiest cloth class and feels like the heals are OP. IMO they felt nearly indestructible in PVP and ripped my hair out every time I fought one.
Shaman- Feels like its better in melee Format vs ranged, Highly bursty but not much else to comment.
Druid (Boomkin) - I didnt get to practice this one too much, My damage felt small so I probably never caught onto the actual rotation of this spec. They seem to be Meta at the beginning of every patch in pvp imo until they get nerfed generally within 3 weeks.
Dracthyr- (Medium range) They feel like an amazing class for open world if theres ever a new expansion where you cant fly, he will get across the map very fast due to having kind of a flying racial thats limited. They are a decent support DPS class due to the racial of giving people faster movement cooldowns and able to get out of snares fast. was a hard skill cap for me , felt better in PVE but definitely fun.
Melee.
Deathknight- Loved its tank version cant get a hang of the DPS rotations of them. Loved them in PVP but being disarmed felt like a death sentence.
Paladin- ME personally did some of the most damage on this class with an auto attack build, loved their utility however if you misclick an ability and go into forbearance for the wrong reason can be a death Sentence.
Warrior- Before Demonhunter existed they felt like they had the easiest rotation for new players, Any race can be a warrior. I feel like I do less damage in Arms VS Fury but Arms is seen as Meta so maybe need to learn rotation better in that spec. They seem to be meta when in full gear but before that get beat down in PVP, Luckily this expansion (DF) has a 1400 rating and you can send conquest gear to your alts, So can easily be fitted into a secondary PVP option when your able to just send them all the gear they need.
Druid- Most OP tank with good heals and armor gain, Rotation felt boring because all you do is see them paw at things all day. Feral Druid felt like the damage needs a rework. I probably didnt get a hang of the rotation.
Rogue- Nightmare in many ways especially in open world, I liked sub the most if a player doesnt die after using your bursting cooldowns you basically vanish and cant fight well for awhile of a team fight. I felt that outlaw had the most sustainability but hard to keep track of all their mechanics. Assasin hit and miss depending on patch but a ton of fun. Had the most fun as sub but took a long time setting up the hotbar.
Monk- In BFA they felt weak to me, this expansion (DF) they seem to be much stronger and do really well at countering both warriors and DH. They have very good healing Defensives in fights. Definitely the most mobile class.
Demonhunter- Just like Hunter they feel like they have the easiest rotation. Probably the most fun cleaving AOE class in the game which does make up alot of their damage and I feel that players dont often account for that. The damage they do to single target doesnt feel very meta imo. I even felt this way before they were considered overpowered and got their nerfs. Was able to get a hang of this probably the fastest and their mobility is pretty fun, Monk feels a little faster. Definitly a great pic for newer players.
After analyzing my data over the course of years and various patches DH has felt the most viable. One of the reasons that I took so long to just not main a DH is because Vulpera was my favorite race and I loved being cute and vicious at the same time but this class feels the most fun. Someone disagreed with me in another thread on DH and said monk was better, To each their own I guess?
Note- this Expanion (DF) if someone reads this thread years later. Maybe this analysis will help out newer players.