SMN is quite easy IMO. Just keep up dots and use cooldowns appropriately. Eventually you get a feel on when to refresh dots so you don't need to watch them.

PLD, WHM and AST are also easy. Paladins have an easy rotation and the two others tend to be main healers who mainly focus on health bars and use their big guns while the Scholar juggles the fairy, shields and dps.

Some say BRD is easy as well. I wouldn't know because I only play it in level 50 content. Personally I would not recommend a melee for a raid leader because they need to focus on positionals and a long rotation.

Whatever you pick, the most important thing is to stick with it for a long time. Just keep doing easier content with the same job until you can fight with just muscle memory and intuition.