Best controll board for LinuxCNC

Which controller board is best to use with LinuxCNC? I have a 3-axis router. DM542 stepper drivers and Nema 23HS9430B motors

The 7i96s is a drop in kind of replacement.
At the risk of adding far more complexity, you could consider Ethercat. There are some interesting options emerging. eg The Lichuan 4 axis stepper driver in a single package. I only hope I can get this going, Also available in closed loop. At USD $92 plus shipping, it competes on price depending where you live.

 
 

As I understood open loop drivers and motors are existing and are kept in the system. (for the time beeing)

It is probably difficult to answer the question. What makes a controller better (best)?

• cheap? (two parallel ports (PCIe cards) in old office PC)
• least amount of re-wiring? (existing parallel port machine?)
• cheaper? (but not a bit of documentation) ( FPGA cards of unknown origin)
• Is wasted time cheaper than money spent?
• easy to set up? ( pnc config)
• upgradable? (linear scales, tool changer, rigid tapping, closed loop positioning, linear motors)
  
  I used an old parallel port machine, changing form mach3 to LinuxCNC was 90% figuring the "charge pump" out (no re-wiring, all in software), then the computer quit service and the replacement had no parallel port. (a 10$ PCIe card fixed that). 
  Having problems to get an encoder running a Mesa card (6i25 with daughter card) went into the machine. (solving the spindle encoder issue)   (it still is a Frankenstein mixed Mesa and Parallel port). 
  
  Greetings Timo 
  
  p.s. the UC300ETH is that working with linuxcnc? Some older threads stated it does not work.
  forum.linuxcnc.org/27-driver-boards/2982...moothstepper-to-mesa