A noob with.... a doubt....
If you like good condition damage you should pick the Mesmer, cause in its current state the Necro is way inferior in this field. Also the Necro has still a lot of bugs (over 90 are confirmed), so it’s possible that you won’t like him much.
The Mesmer has some minor bugs too, but he’s very effective in both PvE and PvE. He is also not that one-dimensional as a Warrior.
The Ranger would be my second choice.
Occam Pi (Ele), Acaena Elongata (Warrior), Finja Salversdotir (Ranger),
Bytestream (Engineer), Vim Whitespace (Thief)
I hear necro’s have a very high number of class specific bugs at the moment. Might want to hold off there.
Warriors are…warriors. Pretty boilerplate as far as I know.
Rangers are very fun ranged, or melee DPS. They’re a very versatile class. They’re my favorite class thusfar. They have excellent survive-ability in PvE. If you learn how to stay very mobile and use your avoidance skills properly, you can stay alive though ridiculously unbalanced fights. They’re NOT as good at PvP from what I hear though. I haven’t tried.
Mesmers are fun, if a little weird. I hear they do GREAT in PvP due to the nature of their clones and how confusing that can be for your opponents. Plus, the Shatter abilities are good for AOE damage.
You should just roll one of each and play it to level 10 to see what you think. I have a friend who rolled one of each class and played to 8 to figure out which he wanted.