Anything would be good seriously.
Elementalists blow up stuff faster than a nuclear bomb, but squishy as hell.
Mesmers can hide between their clones, but lacks aoe.
Necro is the king of open world, but lagging behind in endgame pve.
Ranger is the standard pet class, you wont ever know what agro is.
Thief if handled well can take on half of the map, but one mistake and you are dead.
Engi is the swiss knife of GW2.
Guardian is the good guy in full plate and refuse to die.
Warrior is the ultimate safe choice, just slam your head in the keyboard and breeze through the levels without knowing how to play.
Get a class that you enjoy playing, master it and you wont have any problem.