I find myself torn between the two. I've currently got a rMBP 13", and want the option to use an external display. I'd prefer to stick with Thunderbolt, so I'm looking at either the Thunderbolt display or a Mid-2011 27" iMac. Size-wise they're pretty similar. The iMac is a bit thicker, but has a Superdrive built in - which I don't have and need to buy. It also includes a Magic Mouse and Wireless keyboard - other purchases I'd need to make with the Thunderbolt Display. As I understand it, I'd only have the option of using the speakers on the iMac in TDM. This isn't really a big deal, as I don't use a lot of USB peripherals, and rarely use a webcam. The Thunderbolt display (refurbed), along with the accessories I need would be $1050 or so. The iMac is $1130. The iMac gets me all the accessories included, as well as a second, slightly more powerful (and upgradable) Mac. I don't particularly *need* the second Mac, as the rMBP covers most things well, but that's not to say that I won't make use of it if I have it. Which is the better option?