Like the OP, I too have a 2014 iMac 5K 27" with 32GB RAM. I had my eye on the Mac Mini 2018, which I plan to buy at the end of the month. Then I heard that they announced the updated iMac, which tbh, doesn't look that impressive, other than the i9. My 2014 model had thermal issues, which were fixed, but now it has screen ghosting issues & no longer under warranty.
Because of the issues I've had with the current iMac I have, I'm not interested in another all-in-one. My younger brother also has a newer iMac than mine & he's had a lot of issues with it. He also had an older model, which again, had issues.
I'm currently looking at roughly $2,500 for the Mac Mini I want, if I go with an eGPU (unsure if I'll need this or not). That part depends on if I ever decide I want to game on it. I could be wrong, but I don't think I'll need it for Photoshop or Clip Studio. Main thing I use my computer for is watching anywhere from 1-5 streams on Twitch. Which again, I don't think needs the eGPU...? That price is before I get 2 monitors though. Currently have this iMac resolution set to 3200x1800,so was thinking 2 4K monitors with the Mini, which I didn't price into that cost.
Another reason I want to go with the Mini is due to I think the iMac is limited on additional screens. Obviously it's default 5K monitor, but I don't think you can connect another 5K to it. I know I think I read the 2014 can't, so maybe that changed. The Mac Mini can do 2 4K monitors at 60Hz + an HDMI monitor. What I don't know is if this changes with adding an eGPU. Obviously it would be depending on the ports on the eGPU, but would an eGPU do something like... 2 5K monitors? Co-worker of mine, which is also a Mac user, suggested I looked into ultra-wide monitors instead of standard sized 4K monitors. Another thing I know nothing about is wide screen monitors. For now, I have a 27" 1080p (current 2nd monitor to the iMac) and I think a 23" 1080p monitor in storage.
So after all that rambling, I'm still not sure what monitors I'd go with for the Mac Mini, but is very likely the purchase I'll be going with.
Edit:
I see we have a 28 page thread all about the "best" monitor to get for the Mini. Suppose I have a lot of reading to do.