Every class has its perks and none are terribly difficult to pick up. And most have their own unique skill types, but playing around with any one will get you used to it pretty quick. You also get to pick up a secondary class, and swap secondaries later on. The only things unique to your class are your primary attribute, armor rating, and energy regeneration.
Warriors are straightforward melee combatants, Assassins are combo-based melee, and Dervishes are spell/melee hybrids with a lot of self-buffing.
Rangers are medium to long range archers with pets and Paragons are medium range combatants with a variety of support and party buffs.
Elementalists are high damage casters with many area-of-effect abilities, Mesmers are disruption casters with some surprisingly high damage options, Necromancers are debuff and minion based casters
Monks are the primary healer and damage mitigation class, with some niche offensive options, and Ritualists are a mix of healing and turret spam
Just play whichever feels most fun. make a couple characters and play around and you'll find your niche.
