Is one mental illness 'better' than another? (And, chances are, you know someone who is delusional)

If you had to have a mental illness, which one would you choose?

Would you rather be afflicted with Depression? Anxiety? Bipolar Disorder? Schizophrenia?

Most people probably choose along these lines:

People often think of mental illnesses as sitting somewhere along a spectrum from "better" to "worse". Schizophrenia, with its delusions, is knocked as being "the worst". After all, what could be worse than a complete break with reality?

Well, in reality, it's not that clear cut.

To associate delusions with Psychotic Disorders alone would be a gross mischaracterization.

All mental illnesses range from "mild" to "moderate" to "severe".

Delusions are a common link between the severest cases of each type of mental illness.

Severe cases of each type of mental illness (depression, eating disorders, PTSD, OCD, etc.) all involve some sort of "break with reality".

Think about it this way:

A delusion is an unshared, unshakable belief in something that is clearly untrue.

No argument (no matter how compelling it seems to everyone else) will convince the delusional person that their belief is untrue.

Here is an example of paranoid and persecutory delusions characteristic of schizophrenia:

A 20 year old college student living in a residence hall firmly believes that "the cafeteria food is being poisoned, there are cameras hidden in all of the light fixtures and also behind the mirrors. Every black car on the road has been sent by the CIA to follow me. They're watching me all the time. They're monitoring my every move. I don't know why - but I know with 100% certainty that it's happening".