Look up the most dangerous cities per capita and see which ones A. have nice neighborhoods that you could live in or B. allow you to live outside the city.
Philadelphia Fire Department is very busy (probably busier than any service mentioned yet) and has a good amount of violence, though EMS has to compete with PD for the shooting victims. PFD likes to burn through medics and the medical director doesn't have high standards, but there are some damn good medics working there. PFD is hires frequently
I would imagine that Detroit FD has a good amount of turnover and is busy similar to Philly, and, they do have a per-capita murder rate that is twice that of Philly.
Newark NJ is covered by University Hospital EMS, which probably has one of the busiest ALS services in the US. Have fun trying to get hired with only transport experience, I don't know how much leeway they'd give you with only BLS 911 experience, even if its in Boston.