I would say Ana.
Ana can heal from long range. It’s good in a 5 dps game where those dps are usually splitted.
Moira is just horrible : you past your time running at some allies, while the other ones die.
And when you dare to have a little fun, or recover your heath-charge, you get called a dps moira.
Zen is, like ana, really good. It’s easy to heal with your orbs to these 5 dps.
But you don’t have the burst heal ana can have (but you don’t have to aim)
Mercy : i don’t know i never played that hero.
Lucio : Same like Moira’s case. When all your DPS are usually splitted it’s not revy effective.