Zeus - I have not flown with it but based on a demo and reports it is now very equivalent to the LX9000. Now, because it started later and had catching up to do.

Two specific points of comparison -
the LX X0X0 range has more flexibility in how you setup the screens using LX Styler than the Zeus, I like this but it would not matter to pilots who use the default setup or something similar.
and the Zeus uses a logger external to the computer unit so will be much easier to arrange calibration checks.

On ease of use in flight - 2 of the things I use most often are volume and zoom, I like having dedicated knobs for these rather than the CN interface. But I am sure the CN wins of these three on ease of use without learning time.