ana.
Her kit is unmatched. She makes Bastion and hog pretty sad and her sleep can save your team. Her healing is insane when grenades is used on team mate..
Easiest, moira, heavy healing with high mobility make her my first pick.
Zen for defensive ult and help DPS counter heavy healing/pocketing
Lucio more like a area control support capable of pushing away threat like mei and help the push or escape différents situation.
Every support his awesome in the role it need to fill, but ana is in my opinion the best support hero in the game..
Mercy because how quickly she can move across the battle field and have access to high groud