Mnk and drg and nin is pretty much the best melee at moment with instant burst damage and escape ability.
Also at high rank samurai is hard to play during sam has no escape ability and shield require cast time + 2 target and chiten 25% reduce 5s is bare any use during how high damage output is from rest of dps. So sam can only join middle of fight instead dive in at begin or after burst damage from enemy team.