One-on-one combat? No pets? Giant barbarians squish EVERYTHING. They have lots of disadvantages that come out somewhat in group combat, but in solo PK, barbs are the way to go.
Close second goes to swashbucklers. Generally, half-elves make solid swashies, though sprites can hold their own, given some equipment. Elves are faster than half-elves, I think, but not as strong or durable. Swashies can rip quite a lot apart just by the sheer volume of their attacks, and they're hard as hell to hit, what with carrying so little and eparry, but a decently equiped giant barbarian with no spell buffs will own a decently equiped half-elf swashbuckler with no buffs.
Easy to play? Not as much as rogues or scouts. Scout with a trinoceros pet and a good bow can do some serious damage. In the wild, they're hell. Rogues just buy their pets, but with circle stab and a good stock of scrolls, they can do a lot. And you have to work to catch them afterwards. Besides, they can afford almost anything, what with steal.
Basically, barbs are for squishing most anything. Swashies are kind of like that, just less tanking and more dodging. Scouts rely on hitting their opponents when they can't hit back. Rogues just play dirty, and win that way.
Whatever you do, don't make a necromancer. Newbie necromancers like me are almost as easy to kill as newbie necromancers like Seromet.
Have fun.