Reaper and Red Mage have incredibly similar foundations so I'm not surprised you went from one to another easily. I personally found myself rolling from Red Mage to Reaper this tier.

Reaper is probably the easiest melee, at least as far as I've heard anyway. If you can get the hang of double enshroud then the rotation is fairly simple to grasp and repeat. I haven't had any real issues with it this tier. I am unqualified to speak about the other melee but I often hear SAM isn't far behind RPR.