Finding the FET with lowest channel length modulation
Long ago I went through a similar search for BJTs with the highest Early voltage. My finding was that higher voltage devices had a higher Early voltage. Turns out there is a fundamental reason for this that I won't go into.

Instead of using a high voltage device, I switched to a cascode design, which greatly increased the output impedance.

It is possible to stack more transistors into the cascode and increase the output impedance even more.

With FETs, a dual-gate device does the same thing as a cascode, but in one device.