Lyme disease is unpleasant, but at least North America doesn't have Russia's tick-borne encephalitis, which kills or causes permanent neurological damage.
Rocky Mountain Spotted Fever has case fatality rates well above 50%, can cause multi-organ system failure, and has a 20% hospitalization rate even when treated.
It's transmitted in many of the same places Lyme is.
Lyme disease can also kill and cause neurological damage.