Who do you think is the best support champ and why?

And what are their pros and cons?

Example:

I think Sona is the best support . Pros: Great early damage. Heals . She has a stun ultimate that makes for some great plays. Her E makes for some good escapes or engages. Cons: She's Quishy. Blitz and Leona use her as a seasoning for feeding their adcs. She's mana thirsty. Her mid game is awkward. She's easy to pick off on her own.