Digital vs Analog signal for data transfer across boards
Sending the digital signal is the better option, as it will be less susceptible to interference, or distortion as it travels between the two points.

Along the way not only can the sensor pick up noise from various sources, but losses along the sense lines can distort the reading.

Sometimes sensors need to be placed far from the ADC due to environmental or other conditions (high heat, etc.), in which case those distortions are taken into account during the design of the system.

Place the ADC on the sensor board, and send the digital signal out from there.