I have treatment-resistant schizophrenia. I've been on just about all the antipsychotics you can get, sometimes two at the same time. The only one which has worked is clozapine.
Since I switched over to clozapine, lithium and venlafaxine, things have improved massively.
The main problem with clozapine is the regular blood tests which can be annoying, and if you get a red blood result (low white blood cell count), you need to stop taking it instantly, no matter if it makes you worse. Thankfully that hasn't happened in the last year.