Moira, but very essential to use your heal orbs. Most Moira Main Beginners have the mentality of being DPS instead of a support so definitely focus on keeping your teammates alive rather than getting picks. REMINDER: Moira healing spray actual lingers when it hits your teammate, so you don't have to waste you spray ammo. It also has a pretty far range, so definitely practice with that.
Moira Lucio & zen you'll get real far with those. Ofc knowing Ana too is good but as someone who plays all support except her in comp I'm doing just fine
I main Moira and Zen. Lucio is more for mobility and helping other healers give out more heals, and Ana is more focused one by one heals, and grenades. Moira is generally in every game, so if you want meta stuff, it's her.