I just bought a 2017 27" 5k iMac from the Apple refurbished website. Moving from a Windows machine. My configuration is the 3.4 GHz i5 processor, 16 GB of Ram, 4 MB video Ram, 512 GB SSD. Added a 1 TB external SSD for extra storage. This machine is plenty adequate for daily use in my opinion. Very smooth, very fast. I haven't loaded it up with lots & lots of software, but I don't plan to.
Just using the included applications I've been doing video capture and exporting, viewing 4k videos from my drone, photo editing, lots of internet usage of course, things like that. It seems great. Copy speeds are plenty fast.
Yes there will be new iMacs coming, but at what cost? And how much power do you really need? Those were the questions I asked. My goal was to keep the cost as close to $2,000 as possible or lower. The external SSD pushed it a bit over but that's ok. I added the Magic Trackpad as well. It seems a little costly but it's super nice to use. No issues at all with gestures going back in Safari or anything else. It works great. I had a trackpad for my Windows machine also which I liked, but this one is so much nicer.