Well for the supports in question:
Braum's a handy with his Q which does a lot of damage early on for slow, with the W for positioning and bonus armor+mr the E's projectile shield's pretty nifty when there's someone like a Jinx on the enemy team. And the ult knockup's just fun af \o/
Alistar's WQ combo's great, he has a small heal and his ult's so nice even if you're behind, ...tho if you're really behind you'd get killed instantly anyway xD the headbutt also works when you have to disengage to butt the enemy's damage dealer away
Blitzcrank is just Q+E+W+R=ded whether it'd be you or your adc doing the kill.
Thresh is hooks for daaaaays and QE works for cancelling their escapes route and the lantern for getting your ally quickly at your place. Ult's a great slow imo too.
Janna, now I haven't played all that much Janna yet but her Q knockup W for passive movement speed and slow the E shield and AD boost and ult healing,
Soraka=Heal me! Heal me! low health? Just Q some enemy champions! global heal!
Leona I used to main her but I kinda haven't player her a lot even tho she's my first bought champ, at lvl 3 she's an engage monster.
Morgana's fun tho I haven't played her enough yet like Janna but she has snares, the AoE damage and spellshield+if the ult works a stun.
Nami has bubbleeeeeeees and waaaaaaaaves and heal and the attack buff
And I might've forgotten any other supports but this is what I think so don't take my word for it hope it helps \o if it doesn't oops