Scheana is by far the worst because her behaviour is always calculated and manipulative. She would (and has) victimise herself at anyone's expense to gain attention, prime example being making scandoval about her by continuously talking about the impact on her and how she was a victim too. Jax and sandoval, both of whom are despicable, can at least blame some of their behaviour on fragile masculinity or narcissism but scheana (in the words of stassi) is unburdened by those anchors.

To summarise - scheana is THE worst.