The fluid mobility, high sensitivity, precise turns, etc. 
Any hero that involves sharp camera turns and animation cancels I would imagine
There are pros and cons. Dashes are easier for Genji with a mouse but general movement is hampered with a keyboard. Fist is easier with no aim assist, though. Itβs tough to land abilities with him when the crosshair speed is interfered with by enemies moving through it.
the ONLY thing i love/like about controller joysticks is trigger spring buttons in single player games. i like how it controls in grand theft auto or similar car controls for speed variance and also love that you can RP walk easily, wish keyboards had some kind of trigger speed key
I mean, itβs also alot harder to track a Genji or Doomfist using all of their mobility abilities, so I think it evens out.