C dividers are safer at high voltage and lossless.
then decide if delta or Y
I sensors may be expensive CT or cheap but custom Hall sensors
then scale to your ADC range , add filters and decide if you want Vavg or V pk or true rms and convert accordingly
Decide on range, accuracy, and metrics 1st
eg. mean, std dev, peak , transient pk, V-sec of surge impulse. brown-out durations, interruption interval, imbalance etc , p.f.
For protection use series R and gas tube, TVS , spark plug etc. and choose R to limit below holding current of arc.
then filter and use twisted pair shielded or 50 Ohm coax with suitable drivers.
For bonus points , include a Partial Discharge V-s and pico Coulomb, peak detector, a common fault in power equipment used for Condition Monitoring and maintenance.