I would put down a list of hardware requirements: CPU, Memory, Disk (speed/size), screen, connectivity.
wrt Mac: It just works and most of your unix tools are there. You might still need a VM depending on the task as OS X is not Linux.
My current setup (around 2,500$): mbp 13' retina, 16g ram, 256g SSD. Asus PB278Q, CM quickfire keyboard, apple mouse
I would also consider Dell XPS 13, although it is at the same price range as mbp retina.