Richard wants to upgrade his Mac Mini to an iMac. What's the biggest bang for the buck, the 21.5" or the 27"? Leo says to get the larger screen if you can afford it. If not, why not just get a new Mac Mini? Richard always has a screen, mouse and keyboard. The Mini has been upgraded and is now a pretty compelling product. You can get a six-core i7 Mini with a nice SSD and RAM for less than that iMac. Or if you need the iMac, go with a six-core i5 and the Radeon Pro instead of the i7. It'll save you $200 that you can put into more RAM or the larger screen. The downside is, it has a fusion drive in it. So upgrade to the SSD drive for it instead.