I use a 2012 MacBook Pro 15". I bought a second hand as it was the last mac laptop with a nvidia card. Not the fastest but makes a difference for most machine learning calculations.

It's got 16GB but it's not quite fast enough for my taste. I find myself waisting time on Twitter or HN when compiling or training models or running integration tests.

My ideal laptop would be a 13" mac laptop with a 4K screen, a nvidia card with 3GB of ram, 32GB ram and a nice fast 512GB hard drive. Perhaps it can have a thunderbolt so I can hook up an external 1080 nvidia

Sadly I realize Apple is never going to release such laptops.. I'm describing a Razr Blade or a DEll XPS :(