Main GUI is a 12-core desktop with 32 Gb RAM en two 24" monitors, but that desktop has direct access to at least 12 other Linux boxes that all serve their own goal (databases, services, git, storage, ...). Next to the displays is my 4-core laptop that is used for trial-and-terror, REPL, experiments and documentation.

Never had any Desktop. Around 2004 my son gave me a Dell 38GB laptop with Debian Sarge(Gnome 2 DE)/Windows XP double booting. LaterI erased XP to get more space. From 2011 I am using Dell Vostro 1014 laptop and last January acquired another Dell Vostro 15 3558 laptop. The OS was always Debian Etch, Lenny, Squeeze, Wheezy and now Jessie. After the arrival of Gnome 3 switched to Mate DE.For some time around 2009 I had opensuse 9,10,11. Really picked up the linux flavor from opensuse users' forum.

A Dell Latitude Laptop docked to an external display and keyboard. I use the laptop as the second display and couldn't live without it! If I need to take it with me, I pop it off of the docking station and I'm gone. We live where there are numerous power glitches, so since laptops have their own, built in "uninterruptible power supplies," that works well, too. We have five office machines, all Dell Latitude laptops. They have proven to be bulletproof, super-dependable and easily upgradable and reconfigurable as well.

I'm not sure I have one...
I spend my day working on Windows laptops provided by my employer and customers.
at home my desktop is my "TV" (I could tune into digital TV but rarely have the drivers installed), music system, gaming rig and VM host and it's on most of the time I am awake at home.
however, as it's not set up as a desktop I spend a lot of time typing into one of my laptops -- that and the desktop only has two screens and I may be using both already.
Then, when travelling or not at hone or work my phone gets used a fair bit to visit here, use IRC and the like (much as my laptops do at home).

I think that, ideally, I'd carry a 7" (or thereabouts) laptop-style device everywhere and plug it into monitors and external keyboards where present -- sadly devices that size don't yet compete with my desktop for performance and the laptops which do would cost too much, get too hot and be too heavy to bother even taking into the kitchen to watch YouTube.

I see it is following the question elswhere and my reply there was noted!!

Desktop is king imo.

Laptop is my main machine. I also use a smartphone without the sim card, airplane moded, with a linux terminal running for when I am on my feet and need to enter data.

I have several desktops and several laptops as well, but my main box, on which I am typing this response, is one I built myself (which is getting a tad long in the tooth) and on which I run 64-bit Linux Mint 18.1....

Henri
Registered Linux user : #451735

Windows Laptop for games - most browsing - I want this to be a virtual Windows for the gaming
if I can manage it

Ubuntu server for most computing

Mint laptop remotely, Mint Netbook occasionally for remote

Up until a couple years ago, it was a desktop. Right now it's a laptop, maybe being sort of an extention of my desktop. My laptop is only a i5-6200 with 8gb of ram, and 256GB of storage. My desktop is an i7-4790k with 32gb of ram and over 6TB of storage. I use ssh/sshfs quite a bit between them.

Laptop for business computing (professional coding and debugging, email, calendar, messaging, presentations, etc), although I use a VM on a private cloud for testing. I use a desktop for home computing (budget and investment tracking, music, photo and home video editing and archival, etc) and a tablet for private emails and casual internet browsing.

A brand new AMD FX with a Radeon RX480 graphic card (unfortunately not yet recognized with the correct driver, help needed) using AV Linux.

I have finally found the perfect setup.

Although I have everything on the list except a notebook, my primary machines are desktops.

Ubuntu desktop, with Android phone as a poor second.

17" AMD 64 Laptop (though it says it is a notebook?!) is my primary device. Have 10.1" Android Tablet and Android Phone...but routinely switch over to the Laptop: depending of course on what tasks I am working on.