Huge damage combined with loads of healing and buffs to increase armor. The survivability and access to major buffs on my Warden is unparalled to any other class I've played except maybe a Dragonknight even then the DK doesn't have a burst heal.
Wardens have burst heals, heals over time, free stamina/magicka return that costs nothing and grants you Major Brutality or Major Sorceror, a heal on light and heavy attacks that heal for 7k+ not even specced into healing passives and while active grant Major Savagery. Let's not forget the passive that Grant's Major Mending on healing under 25% health to keep you away from death.
Combine that with abilities on the defensive side that gives you Major Resolve, Major Ward coupled with Minor Protection, an ult that Grant's Major Protection and does tons of damage without even speccing into it. A skill that absorbs massive damage from projectiles and Grant's Major Heroism and a skill that has access to Major Endurance and increased Stamina Recovery.
In short the class is so loaded on sustain and survivalbility combined with heavy burst damage it's hard to play other classes.
I can 1vX in Cyro on a Warden getting hit by 5 people and still escape, the DK can do the same and has good survivalbility but still the burst heal from Wardens combined with massive sustain and heals over time make you so damn tanky while supplying tons of damage output.
Only class that can tank, heal and DPS without being particularly bad in any aspect.
Warden has ruined any hope of enjoying other classes, in your opinions what do other classes bring over the Warden? and what makes you play other classes over Warden while being disadvantaged to them?