Unfortanly there is not much information about which controller is the best choise.
Leetro is most used I've seen on the market but is it the best? Ruida and sinjoe seems to be more modern and kept up with the market.

it's hard to compare these items but i think they are one of the most important items for the machine.

At the moment I'm in contact with several factories, and they can all build custom machines.
With my budget of 4000 (euro) I want a 6040 machine with reliability and quality.

Already had replaced multiple parts to upgrade the machine. Like easy servo (hybrid) drivers from leadshine (2 Nm).
And reci 80W tube with original reci power supply.
2x netfilter to ensure clean power supply (tube seperated from the controls).
Wider belts (german quality).
Up and down table.
and more.