Some warriors are actually killing in banyo faster then sins with aoe.
I would also like to say a warrior will definitely beat sin hands down if played right with matching top end kits, considering a double bladestorm with decent luck will kill a 3.5k hp sin without crit. It takes only a second to deal that damage. Sin requires 8 seconds to kill the warrior (4 lotus)
With all that said warriors run macros so don't ever double bladestorm haha.
I play a sin and would say they are easier to play. Less kit depending to hunt the higher content due to life steal. However once in trouble they die fast, having no fetter or assult to escape means if they stop hitting they die pretty fast.
Either class is good, but I would observe a few top players before making your choice
Also life steal is viable on warriors now with there aoe attacks working, pig level 10, Tao spell, new LL wep are the source for this so it's not easy to obtain.