15" rMBP (£1799) or stock 27" iMac (£1699 one)

[iancapable]

Hi, struggling to choose between these two machines... I don't necessarily have to be mobile (I have my work laptop - windows and my ipad, so I guess I am covered there). I have a set amount of money I can spend, so the choice will be of either of the two off the self versions - The cheaper £1799 macbook pro with retina, or the more expensive 27" iMac (of the two 27" imacs). I am not worried about storage on the macbook, as I have plenty external storage all over the place. I was more worried about memory and hdd speed.

For example I can spend £100 or so on getting the iMac up to 32GB of ram, but would be stuck with a standard 7200rpm drive that could only achieve a max of 70MBps. Or I take the nice macbook with 256GB SSD that reads and writes around 500MBs, but only has 8GB of ram.

8GB of ram is probably enough for me, give that I can dual boot on the macbook rather than VM. I have 12GB in my current late 2009 iMac (27")