The discussion as to whether a certain class is extremely easy to play or not seems to never die. Considering the changes that Blizzard continously do to the game, classes can go from being easy to difficult and back to easy again in a matter of months. And it's really interesting to see everyone call something "faceroll", except the ones who are targetted as the facerollers. It is also interesting to see that most people would call any class but their own "faceroll" in the right circumstances. Why do we all think we're having such a hard time?
But first, some clarification is needed. In the game that WoW has become there are few classes that aren't easy. If by easy I mean "can get to 80 fairly fast and not do sucky dps unless you're retarded". There is a world of difference between a class that has an easy time doing things ok, and doing things great. When people say that something is "faceroll", they generally seem to mean that the class has an easy time to do a great job. Topping dps meters isn't much of an effort. But of course easier doesn't have to mean easy at all, but still easier.
So what is an effort? What makes a class more difficult than another? Easily explained some classes have a rotation that is easy to control, whereas the more difficult dps classes have a rotation which is easy to screw up and extremely unforgiving once you do. I'll keep this discussion to dps classes, since tanks/healers have a special situation.
There are some factors that decide whether your class will be easy or difficult to do a good job, and I won't take trinkets into the consideration here;
First of all you have the set of mashable skills which make out the basic arsenal of attacks of any dpser. Some have no cds and some do. Most mashable skills have a cd of less than 15 seconds, or it wouldn't really count as a mashable skill.
To mention a few;
Shadow Priest - Mind Flay, Vampiric Touch, Shadow Word: Pain, Mind Blast (sometimes) = 4
Arcane Mage - Arcane Blast, Arcane Barrage (sometimes), Arcane Missiles = 3
Uptimes are different debuffs that you have to keep track of to maximize your dps. They sometimes increase your overall damage without actually doing that much damage themselves, but this differs greatly between classes. You need to know the optimized application rate to get the most of your uptimes. Not all debuffs are worth using at any given time, and some debuffs have priority over others.
To mention a few;
Elemental Shaman - Flame Shock = 1
Balance Druid - Insect Swarm (sometimes), Faerie Fire and Moonfire (sometimes) = 3
Destro Warlock - Curse of Elements (sometimes), Immolate = 2
Survival Hunter - Serpent Sting, Black Arrow = 2
Feral Druid - Savage Roar, Rip, Faerie Fire (sometimes), Rake, Mangle = 5
Most classes have some sort of cooldown skills which for a short amount of time increases the overall damage. You need to keep track of the optimal time as to when to use a cooldown to get the most out of it. To for example use it when you have nothing to hit on would probably be a great waste of potential.
To mention a few;
Retridin - Avenging Wrath
Fury Warrior - Recklessness, Death Wish
Shadow Priest - Dispersion
Sometimes you have to stop what you're doing to use a whole nother skill. A proc means that you have to keep track of all your procable skills and be able to adjust to the proc fast.
To mention a few;
Balance Druid - Eclipse
Survival Hunter - Lock and Load
Retridin - Art of War
There are currently four and a half different resource systems in the game - energy, mana, rage and runes (and runic power). Some classes have to give great consideration to their resources (energy and runes and mana in some cases) whereas others have to think about it way less (Rage and mana in some cases). This makes alot of difference to whether a class is easy or difficult as we will see further down.
Now, my examples are just examples. And I'm far from pro on every class so I have probably missed out on some skill here or there. But the point is that all these things, skills, uptimes, cooldowns, procs and resources decide whether your class is more difficult than another. It seems quite safe to say that the more of these you have to keep track of during a short period of time, the more difficult your class will be to do a good job. Something that is difficult to measure but definitely makes a great difference are different synergy effects between these factors that you'd might have to keep track of to do optimal damage. Synergy can be seen as a sixth, invisible layer that affects all the other factors.
So which class is the easiest?
A quick glance at Arcane Mages will make you want to say they are. But looks can be deceiving. It is true that Arcane Mage-rotation basically revolves around one single skill. But if we look at the other things on the list - mainly uptimes, procs and cooldowns - things don't look that easy anymore. Arcane Mages have one proc to keep track off (Missile Barrage), one uptime (Frost or Flame Ward for Incanter's Absorbtion) and no less than six cooldowns, Icy Veins, Arcane Power, Mirror Image, Evocation, Mana Gem and Presence of Mind. That means that although Arcane Mages only uses one mashable, they have to use eight other skills successfully to do optimal damage. Much of this revolves around using the cooldowns and procs to streamline mana management. And most of these things are on longer cooldowns which means you rarely have to take split second decisions when dpsing as an arcane mage, it allows for some planning ahead.
No, my personal favorite (in easyness) is Elemental Shaman. On single-target fights Elemental Shamans have two skills (Lightning Bolt and Lava Blast), one uptime (Flame Shock) and one cooldown (Elemental Mastery) to keep track of. An elemental shaman usually has no mana issues whatsoever (as opposed to Arcane Mages) and therefore doesn't have to use Thundershock for optimal damage. That means they have four things all in all to keep track of to do good damage, which is less than half as many as an Arcane Mage.
But, which class is the most difficult? If we follow my recipe of "amount of things to keep track of = difficulty level" it seems to be Cat Druids that are the most difficult. They have one skill (Shred), five uptimes (Savage Roar, Rip, Faerie Fire, Rake, Mangle), two cooldowns (Berserk and Tiger's Fury), one proc (Clearcast) and combo points to keep track of. Those are ten things to keep track of, not counting the combo points. The big majority of these skills have to be juggled within a 30 second time frame with different prioritizing depending for example on current amount of energy and combo points (only exceptions are Faerie Fire and Berserk).
Enhancement Shamans are quite tricky too. I'm not sure of all their different skills and such but I always suck at playing them because I feel like they have too many things to keep track of, so they have to be difficult <.<
Like I said, I don't know every class like the back of my hand so these are just my guesses based on my own experiences. Considering all the changes that are being made to classes all the time it is quite possibly some class has turned into the easiest/most difficult besides these two without me knowing about it. But now you can count for yourself and see, how many things do you need to keep track of? Within what time frame? Is resource an issue? And so on.
I'd love it if you could tell me what different skills, procs, uptimes and cooldowns your class and spec has to keep track of! Maybe I can make a list to crown the final easiest/most difficult class.