2TB SSD speeds, on a newly setup fresh out of the box machine bought a week ago (just after Apple kindly knocked off £180 from the 2TB tier; lucky timing!) ...
So now you know the writes are similar to the 1TB, but the reads match the write speeds, so are potentially higher than the other SSD sizes (though as no one has confirmed the specific read speeds for the other sizes AFAICT, that's not completely confirmed).
Hence depending on your usage, it might be worth getting the 2TB (or at least the 1TB) over the smaller SSD sizes.
I have the i7/16GB/256GB 2018 Mini and have been considering how best to handle my media needs.
Silence, speed, and price were the priorities in decreasing order so I went for an external TB3 NVMe.