Measuring 0-240v 50-60hz Mains AC with Arduino/MCU
simulate this circuit &ndash; Schematic created using CircuitLab

Try to combine both solutions - bridge rectifier and RC-filter combined with voltage divider.    

Although your device is handheld and powered from internal battery using triple resistor divider will no cause 'common ground wire' problem. Only errors of measurement.   

Because you are talking about meassuring of AC Voltage - there will no be 'reverse polarity' problem.