Hardware wise, I really like my Surface Book. It's been my main machine now for over a year. I actually use the tablet mode quite a bit. And, I can't dev without a touch screen anymore. So handy for scrolling! In terms of its software, my favorites are probably VSCode and the Hyper terminal (both Electron applications... yay JS!!).
Otherwise the only hardware I always have on me is my phone. It's an S7 Edge, but I don't like the curved screen at all so I could live without it personally ;)