I bought a refurb iMac i5 ( quad core ) 2011 model a few months ago. not top CPU spec, but I got the reseller to put in 16GB or RAM.

a 2.7 Ghz i5 works fine for me and i'm using very big sample sets.

these days i reckon even the cheapest spec will be fine but my advice is to always go for a big HD and lots of RAM.

The later Macs now all come with 7200 RPM Hard disks so thats not and issue,

Big Sur, Mac Mini i7 2018, 64GB RAM 2TB SSD
Yamaha PSR SX 900, Cubase, Ableton, UNIFY, OPUS ORCHESTRATOR, MASCHINE, Vienna Ensemble Pro ,Audiofuse, L6 HELI, KOMPLETE, Komplete Kontrol 88
Lockdown beard, podgy face, beer belly, bald patch ... yadda yadda