I got the 2.6Ghz/16GB/512GB model. I didn't think the 2.7GHz and the 768GB drive were worth it for what I wanted it for. The 2.6GHz is a bit more powerful than the iMac this rMBP replaced, so that was my main requirement. And the 512GB is plenty since I keep all my heavy media (movies, tv shows etc.) on external drives attached to my Airport.