Lenovo Yoga 510, with the RAM upgraded from 4 to 8 GB.
It’s not a power house, so to say, but I don’t really need that. I sometimes switch to road warrior mode, and in those cases, I need a flexible, easy to carry notebook. It can even be folded to be a tablet, which is extremely useful in some situations. If I need actual computing power, I login to our company infrastructure, which has a lot of CPU cores and RAM altogether.
As an OS, I use Fedora 26 with the GNOME desktop. Our development targets Linux machines (although production code runs on different Linux flavours), and I’m actually much more familiar with Linux than Windows or OS/X.