The obvious answer would be Google Home. Google Home Mini is much smaller, as the name says, and lacks a lot of options that Google Home possesses. Google Home Mini, unlike the normal one, lacks the top touch controls. Also the microphone is much poorer and the volume quality/loudness is way worse than Google Home.
If you are short on money or space, just go with Google Home Mini since it is exactly twice cheaper than Google Home, but if you are seeking for high quality, go with the classic Google Home device