I think OP has a 48volt setup.
The INA226 has an external VBus input if voltage measurement is also required, the 3221 has not. Up to 16 INA226 boards can directly be used on the same I2C bus.
The shunt must be low-side, because of the 36volt common-mode voltage limitation of the INA226. But even then, the INA226 can measure bi-directional (-75mV). The LM324 can not.
Leo..