Sins are easier to start out with, but since everything is so easy to get in game you can start out with any char and do fine. as for PK it is active. Any char is good for PK if you know how to play them. GL and welcome to EPW
Sins wouldn't be the most recommended class to start with if you're low on ECs, since they take the most to get the needed stats to do anything good. It took me 60k ec to get 2x interval on wrists, 25k for interval on top, and 11~12k ec to get gof + atk lvl on daggers.
you're probably right if you want best stats and equips on your first char. if you want to just start out the game with a good farming class imo sins are ok and also if you are new to the game sins are handy since it's easy to play. also if you want the best r8 bonuses for any char you're going to spend tons of ECs anyways.
how flashx got that wep?