When I start playing a game I always choose the class I like the best. In my case I like agile classes, you know, high Dexterity/agility, quick attacks, high evasion. I usually pick the rogue class like aassassin in GF, whatever name its given on the other games. However, before I start playing, I look at the class descriptions and sometimes go with Ranger.
Also, as an alt, I use to pick the healer/buffer.
Dont look at statistics, pick the one you will enjoy.