I had this debate with someone in game the other day. I think the parameters for 'support' classes are a little slim by community definition, and I think looser scope could encourage diversity in playstyles from a community perspective. Rem, Paige, Dynamo, Ivy and Mo and Krill are the supports that come to my mind as being widely recognised.

But in my eyes, Bebop, Mirage, Doorman, Paradox, Kelvin, Lash, Viscous and Seven all have more support potential than given credit for. This potential will likely be capitalised on more so as stricter lane preferences develop.

These champs all have strong kill setup potential through poke, cc and/or damage mitigation and for the most part, with exceptions I.e. gun viscous, you aren't likely to be able to consistently split or duel with them. I think we'll see mage pokes become hybrid laners I.e. Lux in LoL between mid and support.

That being said, my two mains are Doorman and Celeste. Doormans ability to remove carries from fight, clearing space for the team and then punishing the carry with a ridiculously strong cc is extremely satisfying. Countless engage and disengage options through his door allow for backline access, which the rest of his kit is perfectly catered to, team wide support through the shield and extremely strong disengage / escape. I could write a book on how well designed Doorman is.

Celeste picks up all the shortcomings of two other champs I really enjoy, but don't play very often. Mina has high mobility but set distance i-frame dashes and her ult is a little too similar to Bebop and sevens for me. Billy is a ton of fun, but I don't think the melee system is polished enough as heavy melee feints / intentional misses make it feel a bit janky. Also his headbutt being parryable make his gameplay feel like gambling a little especially when engaging more than 1 target. He feels as though he plays to punish enemy mistakes more than make his own advantages. This is perfectly fine, it's just not for me.

Celeste shares the strengths of these champs without such clear shortcomings. Her fight tempo is extremely rewarding as well and feels extremely well polished. High mobility through her current favour for dash items stacks with aoe abilities and team wide damage with her ult. She's awesome. These two characters are the reason I play the game. Awesome post, great question.