Any USB/Ethernet controller suggestions?

[johngoodrich]

personally I would get the uc300eth and UCCNC

[m_c]

For a basic 3 axis machine, then there's not really much to choose between controllers.
You might also want to consider one of the standalone controllers (search ebay for "CNC offline controller" or "CNC standalone controller").

Regards Mach 3 problems, on a basic machine it works fine. There are some issues when you go beyond the basics though, especially with external motion controllers, but nothing that really makes it unusable. It's just quirks that mean you might not be able to do things how you think they should be done.

Mach 4 is fine, it's just it's never really been that popular. Mach 3 was pretty revolutionary for it's time and is why it is so popular, but technology has changed, there are far more options now, and Mach 4 doesn't really bring any major benefits over the other options.