Honestly the best thing is to just try them all. I was originally dead set on playing a guardian, and really enjoyed it the first BWE and stress test. Then my guild decided to make new characters the next BWE to try different classes. I played a Warrior and fell in love almost right away. It became more cemented after the 3rd BWE and playing all of the other classes for a few hours. I enjoy every weapon combo, even the ranged ones (I hate ranged usually) that warrior offers.
Now I'm probably going to make a Mesmer alt way before I make a guardian. It is really a try it before you become committed sort of thing with this game, you might be very surprised by a class you never thought you would like.