What is the best twink class in World of Warcraft

It depends on what class YOU are best as. Hypothetically, if hunters were the best class for twinks, but you had never played a hunter and just can't seem to get the hang of it, then you would not be a very good twink. It all boils down to what class you are most comfortable with.

However, most people are known to pick these classes for a twink class:

Warriors, Protection Tree (for very high stamina and defensive abilities)

Rogues, Any Tree: Subtly (to 1-hit low armor/stamina targets with ambush and easily go back into stealth, very high agility) Assassination (Powerful abilities when outside stealth) Combat (Great combat abilities outside stealth)

Hunters, Any Tree: Beast Mastery (High pet damage, High Stamina for hunter and pet) Marksmanship (shortened Cooldowns, Maintain focus for more abilities, more pvp shots) Survival (Explosive Shot and Trap increase, more pvp shots and melee abilities)

Paladin, Holy or Protection: Holy (Very hard to kill from several instant heals) Protection (Can deal very high damage and take little damage, can gain mana easily)

These classes are often twinked, but not as much for they are harder to use.

Priest, Any Tree: Holy OR Disciplin (Very great group healers, while Disc priests protect all targets 1 at a time easily or the group, holy priests have more group healing spells) Shadow (while giving minor heals from massive overtime damage, they can fear multiple targets easily and avoid taking much damage)

Druid, Any Tree: Balance (Not often, can give massive damage at the start and cause good overtime damage, and avoid most damage from warriors, rogues etc) Feral (Hardest to use in the game, can give massive direct and bleeding damage and can heal occasionally, and can avoid mostly slow effects) Resto (While most heals are overtime, they can easily be stunned or silenced and still be healed from most overtime healing, and if the druid dies after they heal, any healed targets will still be healed)