Motion controllers

[m_c]

For something basic(ish) and not needing anything special, I'd say either a standalone controller (DDCSV), UCNC, or Centroid Acorn.

If you're wanting to do more advanced things, which by the sounds of it you're not, then you'd need to decide on what features you need in a controller, then see what controllers can provide those features.

I'll also echo Chaz, in saying I wouldn't use Mach on any new machines. I only have one machine left that still needs it, but even that I'm gradually working on software so I don't need Mach.

[routercnc]

I’m not going to argue against the standalone controllers, UCNC or Acorn as from what I have seen and read they are great options.
I just wanted to add that I’ve been using Mach3 for years and years on an old offline PC using the parallel port into a free breakout board and have not had any issues that I can recall.
I might be making simple parts perhaps, or only running at a hobby pace but I’m pretty happy with it. I made the current CNC machine with it for example.
They used to have a free version with limited gcode (500 lines) to get you going. Having said that it if stopped working I would review my options.

[Ger21]

UCCNC with their new AXBB-E controller.
You can use Mach3 with it if you want, but UCCNC is far superior and $125 cheaper.
CNC Drive has a UCCNC forum, with a lot of former longtime Mach3 users.