Currently I'm using a 2015 MBP 2.5 ghz quad-core i7 with 16gb ram and iris pro graphics.
I used to have a i7 Surface Book with 16gb ram, but I returned it due to heavy lag in the development module while processing raw photos with 4-5 adjustments (brush, radial filters, graduated filters, etc).
What's your rig and does it work for you?
Get the fastest 4-core CPU you can afford. 8GB or more of memory. SSD optional. You need a GPU that meets the specifications only if you have a 4k or larger monitor.
If you're going to do a moderate to large amount of brushing or spot healing on individual photos, an extremely fast CPU is needed (and I would advise avoiding the 4k or larger monitor in this case).