Playing an Archer is usually the easiest pvp character for people with bad ping since you don't really need to move fast, just stand in the background shooting arrows to help your guild bring down an enemy.
Mage would be extremely difficult to play with bad ping since you have to be constantly clicking things and moving.
Any type of melee skills like fencing or swordsmanship would be in between, you still need to run around to hit people which bad ping messes with, but it doesn't need to be as fast as a mage.