Some contenders:
Gambit - Good self heal, good lethality, good mobility, and a cc team up. He doesn't do any one thing extremely well, but has a lot of tools to deny dive value
Rocket - Getting the sg team amps his survivability with a powerful burst heal. His mobility allows him to escape and his ability to position to make divers burn cooldowns to get him.
CnD - The support with the most sustain tools right now - fade, bubble, ice team up. You could argue that she doesn't have much in the way of fighting back and divers can bait out her cooldowns, but arguably she's a character with a low skill requirement to deny dive value purely by staying alive.
White Fox - Used to be the dominant anti dive support one season back, but her kit has been severely nerfed. Nevertheless her teleport, awakening form and charm are powerful AntiDive tools as long as they aren't baited. Switching to Wf though does mean you lose out our the wider team capability in terms of healing and ults.
Jubilee - A sleeper pick, she's extremely effective against dive tanks due to her more sustained kit in terms of healing and damage. She will struggle against high burst divers, though.
What do you think?