Do you consider bipolar disorder to be the best mental illness due to mania?

Terrible "lows": First of all, the "highs" of mania are more a story about an abundance of boundless super-charged energy (often associated with grandiosity and sometimes paranoia) and not so much a story about happiness and joy. Secondly, the "lows" can be very low and accompanied by suicidal despair.

No: It is a major illness that can disrupt relationships vocations academic work financial security etc. It may lead to jail or suicide mania usually produces irritability which isn't fun--i don't see it as being "best".

Best?: Most fun? Most interesting? Most difficult? It is hard to know what you mean. For those with severe mental illnesses, most don't find a lot of good to having the disorders that they have. Most would choose to have no illness, mental or physical. Manics get themselves in lots of trouble and can ruin their lives and the lives of those around them, especially in the most severe of cases.