Both ranged dps are quite strong right now. Machinist especially if you are more dps focused over utility. With that said, here's my general thoughts on the melee right now (listed from top to bottom, easiest to hardest):

GCD Rotation
Ninja
Dragoon
Monk
Samurai

Cooldown Usage
Samurai
Monk
Ninja
Dragoon

Latency Issues (easiest to hardest to play w/ latency issues)
Samurai
Dragoon
Monk
Ninja

From there, it just depends on how you are looking to play, what you find enjoyable, and what you feel is easier or harder for you as a player.