I spoke with my boss today and he wants to update the board to a ESS to run mach 3 on our windows 11 PC.

What would be a BOB/Controller to buy that would be simple to set up and have minimal issues down the road?

Just my opinion…

If running Mach3 is your only option then the best combination is the Warp9TD motion controller using one of their recommended BoB’s running under WindowsXP.
You must bear in mind that Mach3 is now obsolescent (old) and was developed around Windows95 / Windows98 / WindowsXP and as far as I am aware none of the current motion controller manufacturers still support Mach3.

Ideally you should be looking to the future (Mach4) and re-build your machine so it will be good to go for the next 10 years or more and have trajectory planner, motion controller as well as full Windows11… support.
Again, I believe the Warp9TD motion controller to be the way to go for running Mach4 under Windows11 but, as we speak, there are still bugs being discovered and resolved.

Tweakie.

I'm not against upgrading to mach 4, just Mach 3 is what we have been using.
If I went to mach 4 what controller/BOB would be the easiest to set up and have ample support? The Warp9TD motion controller a good option?

It is difficult to objectively recommend any product but, from experience, I have learned that there will always be future CNC machine operational issues which need to be resolved. To this end support from the manufacturers of both the trajectory planner and the motion controller is invaluable. I don’t consider moving from Mach3 to Mach4 to be an upgrade but rather a move towards the future.
Warp9TD have good support for their product and in my opinion their ESS together with Mach4 running Windows11… it is the way forward.

Having said that I still use Mach3 with WinXP and the LPT parallel port more often than I do Mach4 with the Warp9TD, ESS, Win11 combination. Both setups produce excellent results but each has its own advantages / disadvantages when it comes to switching between rotary spindle and laser usage.

Tweakie.