If there is an Apple Store nearby, check out the differences between Retina and non-Retina to see if it's important to you. When I looked at iMacs, I found that the greatest difference was in the sharpness of text, which was quite noticeable. As to new models, Murphy's Law states that, whatever you buy, there will be something greater two minutes after the purchase.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
| 
