If you want to do any Mac OS or iOS development then the same concerns apply but now you'll be looking at a MacBook Air/Standard/Pro.
I'd also suggest using Linux, either Fedora 27 or Ubuntu 17.10. It helps when your workstation thinks like the server that'd run your code and the person would learn a bit about how to manage servers in the meantime.
This is what virtualisation is for.
Youre not going to be able to run exactly the same environment directly on your dev machine regardless of the OS family, so use the OS you're most productive in, and virtualise for projects.
Vagrant works quite well for this role, particularly if you don't just use the "standard" setup of virtualbox.
Any developer-capable real (i.e. not something running glorified chrome browser) laptop in 2018 will be fine for developer VMs.