Mac Mini or iMac

I do graphic design, plus run my Plex server on my current 2019 27” iMac. 6 core i5 32Gb RAM and a second 27” monitor. It’s becoming increasingly slow to respond so looking to upgrade to one of these in the attached (to the specs listed). I’d look to buy a 4K 45”+ curved monitor if I went the Mac Mini option, but just after some thoughts/advice. Thanks