Are there worse mood disorders besides bipolar?

It depends. Any mood disorder will have a level of severity that depends on the circumstances seen at that point in time. To compare one mood disorder to another serves little purpose and will detract from the treatment needed to effectively return the individual to a more functional state of being. Focus less on the name of the disorder and more on taking effective treatment actions.
Depends Who You Ask. Any mood disorder can be potentially devastating. If you review the mood disorders in the diagnostic and statistic manual (reference source for psychiatric diagnoses), you will see that most mood disorders are classified as mild, moderate or severe. Major depressive disorder, bipolar disorder, the worst mood disorder is the one that interferes the most with your ability to function in life.
Nothing is worse. Brain disorders are like blood pressure we are still learning about brain, i was at tedmed in the company if 2000 brilliant global minds where nothing seems impossible to treat . If your meds are not helping get a consult get on web discuss and read about new meds don't let bipolar scare you , meds are like knife in the right hands of a surgeon they are miracle , in the wring hands they could be ?..?
Function matters. I agree with dr. Woods. When we use the idea of better or worse, we should be specific about functions: physical function e.g.Sleep and appetite , for example, social functioning suh as maintaining relationships, and work function. Interference with any or all of those calls for immediate attention from a psychiatrist.
Mood Disorders. Organic mood disorders such as secondary to progressive organic illnesses ex. Hiv , or mood disorders with severe psychotic symptoms that are unresponsive to treatment.