Mac Mini with a nice screen should do you very well. Posting about Brexit does really not need that much processing - sorry could not resist.
But honestly, unless you are heavy into image processing the Mini should be just fine. And you can keep your peripherals or buy the ones you really like rather than what the regular package normally comes with.
My iMac is older than both of yours and the main reason to keep it going for a bit longer is the excellent screen that I wouldn’t want to miss.
Good luck. A.