Actually im rather suprised no one has mentioned Age of Conan yet, which has, although strikingly similar Input Functions, but is more involving in certain Basic Actions. For one, Melee Classes, and Ranged Classes which do not use Spells, are dependant on Input. There is no Auto-Attack Option and you have to simply press this key or that key to use a certain Skill. There are 5 Angles of Attack, Overhead, Upper Left, Upper Right, Lower Right and Lower Left, that is 5 different Keys for a Basic Attack because every Monster shifts its defence accordingly to a Area where the most Damage comes from. If you attack from the Right, it will defend the Right Side and open up either top or left. Then there are the Skills, which are Combos, basicly you hit a Combo and then press the next Attack Buttons from the 5 Basics to actually do the Combo. For example, one Class has a Combo that opens with the Skill being used and you having to que up (you can only cue up ONE attack after another) in the right order and at the right Timing to finish the Combo and cause the most Damage with it. Again each Combo is depending on its Basic Angle, which is evident on the Hotbar, where the Combo Skill will show a small little silver arrow, which indicates the basic angle of the attack, which again factors into defence.
Players can equally defend themselves by shifting their Defence around to a certain Area, which is especially for PvP or Sidestepping Enemy Attacks that are not ranged, you can foil a entire Combo by simply double-tapping the movement key back, resulting in a small jump backwards out of range of the attack. Of course this is no "real" Blocking/Slashing like for example Darkfall did, but it creates enough of a Balance to provide both Sides with a relaxing Option.
Of course opposed to that Caster Classes, at least those capable of doing Damage dont have to factor in the Basic Attacks or Defence, as Spells bypass that entirely. But again, there are no direct Classes like in WoW. For example, there are no Priests, no real "Healers" in the traditional Sense. There are 3 Heal-capable Classes, each is also capable of causing massive Damage at the same Time without having to focus specifically into one Area or the other. 2 of these Classes are ranged, the third being a Melee Fighter. There is also no "direct Heal", only Heals over Time which you have to manage, you have one Nuke-Heal, which heals about 1000-2000 HP but cant be used more than once every Minute, that Cooldown is shared between Classes, so if Guy 1 of Class 1 uses it, then Guy 2 of Class 1 cant use it either for one Minute. Then there are Blue Heals, which are the second Heal in AoC, it causes a small Instant-heal of about 300-500 HP and Heal over Time, but it does not Stack, so if ANY other Class with a Blue Heal casts it, it will override yours, and based on the Timing, the Team might not even get the full Bonus of the Instant-heal effect. So again you have to pay Attention. The third and last is the Green Heal, which is essentially only Heal over Time and can stack with any other Green Heal but will be overriden if there are two Characters of the same Class in the Group, basicly one Green Heal would then override the other. So you have to pay attention to keeping Heals up, managing Aggro, using Crowd Control Abilities (which they also have) AND doing Damage all at once.
There are only 2 Pet-Classes as such, one is a basic DPS Class which can have one Minion which will, if set so, also attack any Enemy that is attacking you and give a slight Bonus depending on the Variation. It is essentially the same Pet but with a different Bonus. The other is a Necromancer, which has some direct Damage Spells and the Ability to summon up to 8 Minions, depending on which Minions you choose (You have 8 Slots, some Minions take 1 Slot, other more than 1). You can however also specialize in direct Damage and Damage over Time/Curses if you do not want a following of Minions.
So by default, at least in my Opinion, its alot more involving and challenging than WoW. Its basicly what WoW is for Grown-Ups.
Shall save the mmo's. 
