Anywhere in the US is fine if that's your worry. If you don't buy or sell drugs or sex, your chance of random violence is essentially zero.

Now property crime? Not hearing your neighbors domestic violence? That's a different story...

Best is typically everything north of route 9 or May. Or everything along quinsig. If you want 3 specific places to avoid for property crime, Main South, Great Brook Valley, or Lincoln between 290 and 290.