Tingyun and Yukong are both valuable characters in Honkai Star Rail as buffers/supporters for the team.
Yukong is considered the better support option as her buffs increase allies' damage output more than Tingyun's and deal damage as well.
Yukong has more potential to support the team with her passive talent that allows her to break enemy shields easily and her CRIT and ATK stat buffs.
Tingyun has been in the game since its release and she too excels at supporting the team with buffs.
Tingyun's skill grants a benediction buff to increase an ally's ATK stat and add lightning damage to their attacks.
Tingyun's ultimate regenerates energy for an ally and increases their damage for two turns.
Yukong is a new character with abilities focused on increasing allies' damage output.
Yukong's skill grants her stacks of Roaring Bowstrings, which increase allies' ATK stat until the end of their turn, and her ultimate buffs allies' CRIT rate and CRIT DMG while damaging an enemy.
Yukong's passive talent allows her to break enemy shields easily and her CRIT and ATK stat buffs make her ideal for endgame activities.