In the Heart of the Mists you can test out a fully geared level 80 version of your class with any weapon, skill and trait combination to your heart's content against various training dummies. Try making a new character and going right there to see how you feel and maybe it'll help you decide on a class.
If you don't have the desire to level more than one character in the first place, I definitely recommend trying this before you get too deep into the game with a class you don't think you like. You can of course participate in full PvP with this "instant max" character.
The thing is, leveling your character is how you get acquanited both with the core mechanics of the game, the unique mechanics of your class, and the specific mechanics of the build you want to run. Each class has a different curve. I'm not surprised that you had an odd experience with a mesmer around level 15, as they have a quite steep learning curve and the early game before you get some functional traits is brutal. However, they wind up being (in my humble opinion) one of the most powerful, versatile classes in the game.
edit: Btw, I looked back, maybe you ought to give scepter/dagger a shot with your ele? I like it a lot though it's a less common set. You get access to a bunch of the cool dagger skills including Ride the Lightning and some great fields, without needing to get as close in basically melee range to do damage.