What display do I use with a new mac mini?

You can use most any display with the Mac Mini.

see > https://support.apple.com/guide/mac-mini/connect-a-display-apd8e4fbbb97/mac

I use a LG 50inch UHD. Most flat screen TV's will work. They range in cost at Walmart, Best Buy and other retailers. You should be able to find something to match your needs unless you strictly want a monitor.