Regarding the user interface. On my Macbook Pro I have become accustomed to using i3 UI on Linux and now I feel handicapped anytime I switch over to Mac OS or Windows.

The only time I boot Mac OS is if I'm going to be using a browser for a while and can't plug in my laptop. The battery life on Mac OS is much much better.

Just want to echo that i3 is everything I ever wanted on a UI. Everything else feels extremely awkward and slow.

I used OS X for many years, starting shortly before the transition to Intel.

I disagree with the fact that the UI experience of macOS vs Linux is a joy vs pretty good.

That's only true if you compare macOS vs GNOME/KDE. But that's a false dichotomy. IMHO, Linux truly shines on minimal setups without a desktop environment. Of course this is not suitable for everyone. But if you are a programmer, there are good chances that it is suitable for you.

I would never ever switch back from an environment with StumpWM, Emacs, Firefox and xterm to macOS. And that still doesn't factor in the biggest advantage of Linux, openness and a first-class package manager.

Now, you could even take things further and ask for a purely functional package manager and OS. That would be NixOS. Such a setup has many advantages over traditional UNIX userlands worth investigating.

If you are considering macOS, you should at least also consider this kind of Linux setup. All that said, macOS is terrific and a great option for many developer usecases.

What type of rig do you need to run this? Would a Chromebook be good enough?

Any, in principle. Minimal also means RAM-friendly. I can boot into X and open a terminal with less than 256 MB.

Obviously if you add Firefox, you will need around 2 GB to run comfortably.

And then a lot depends on what you develop for.

NixOS is also a bit more disk intensive than other distros due to the way libraries are linked. But it's nothing too excessive.

My favourite UX aspect of OSX is how spotlight works with searching for applications.

If the application isn't already open, it launches it. If the application is already open, it brings it to the foreground.

In contrast on windows, the search bar seems to just be a launcher. In that if the application is already open and you search for it, it opens a second copy. As far as I could find, this behaviour isn't changeable.

Can anyone tell me if it's possible to get osx's search style on any of the nice gui having Linux variants?

If you're talking about an application launcher that's like Spotlight it sounds like Fedora 28 with Gnome 3 would work for you. I've literally only used it long enough to launch a Terminal, but I just confirmed it will switch back to Firefox instead of launching a second instance of Firefox. It also sounds like what Ubuntu has had for awhile with Unity desktop. Their launcher is called Dash.

If you're talking about file search, I'm not sure if they have them or how well they work. In macOS I tend to look for preference files or system files, so I usually avoid Spotlight for file search and I don't have much experience with the other two.

Windows key+1 cycles through windows of the first application, and adding the shift key opens a new window of that application. Just pin the 5-10 most commonly used apps and you're up and away with keyboard navigation.

I rather like Gnome on Debian, the hot corners and search are slick IMO. Never had to use OS X, but the UX is somewhat similar from what I hear.

Then the difference became battery life. It's been a few years since I ran linux on a laptop; has that improved?

It has! I've been using Ubuntu on a thinkpad x1 carbon (2017) for almost a year. Battery life is between 6-8 hours everyday use including work. Probably see between 8-10 if I'm not doing any programming

Similar experience on a Thinkpad T440 with a 1080p screen swap, I can easily go 5 hours before I need to swap to the big battery, which buys ne a few more hours. Games seem to halve that though...

No. Linux can’t match Mac OS on battery life.

This has been my experience as well. Apple seems to have spent a lot of effort in making their software use very little energy. Check out the energy usage of Safari vs Chrome sometime, for example.

Mine has, older Linux on older Lenovo was not good but also that battery was aging.

New (<1yr) Asus gives me about four hours of 30+ tabs across two indipendent chrome profiles, my heavy editor, multiple active ssh sessions, other nonsense, keyboard lights (on low) and screen at 60% bright.

I think it's very good.

I don't have any firsthand information, but I've heard power management has gotten a lot better for both Linux and Windows and the laptops advertise comparable hours (with reviews not calling them out on it). There are a few name-brand laptops that offer explicit support for Linux distros. Those might gave you a better idea of what to expect.