And what is your method of syncing things between them? Do you sync everything or just select things? Just curious as I've only really used one personal computer at a time but the temptation to get a second one is strong and I know others use multiple.
Three computers here: 2015 MBP 13", 2015 MBP 15", 2017 MB, 12". In addition, iPad Pro 10.5, iPad Pro 12.9, and iPhone X. All are synchronized with each other so that if I get an email or a text message on one, it shows up on all of them. All also have my complete iTunes library and a special folder of photos on them as well. I use the 2015 15" MBP as my primary computer, the one which does the heavy lifting and which I consider as a desktop replacement. The 13" 2015 MBP is still here because I never could quite get myself to sell it and I've found that it comes in very handy at various times, although I don't use it daily. The 12" 2017 MB lives in the bedroom and is the machine that I use in the evenings after 10:00 PM or so. I live in a condo apartment and there is someone right beneath me, hence the need to not be staying up until 1:00, 2:00 AM on the computer in the main living area. My moving myself into the other room and getting back on the computer or another device there keeps the peace everywhere. Sometimes i don't bother with the MB and grab an iPad instead (especially on a cold night or cold morning where it's nice to huddle under the covers in my warm bed......)
I use iCloud to sync everything between all of the devices. However.....I keep my machines "lean and mean," so that I tend to accumulate most stuff on the 2015 15" MBP and once a month after a full backup clear away for archival or supplementary storage anything that is not necessary to have on the machine's SSD all the time. I use external drives for backing up and for creating supplementary drives, and that has worked out well for me so far. I use iCloud and occasionally Google Drive for stuff that I want to access from anywhere, but do not put everything on there -- I'm leery of sharing my personal medical/health information or my tax information with the world! Sometimes I'll grab an interesting file or image from the internet while I'm on one or another device, and depending upon size and such, I'll either email it to myself so that the "main" machine will get it, or sometimes I'll just plug in a thumb drive or external drive to transfer the goods from one place to another. To me the value of iCloud is the ability to synchronize stuff such as bookmarks, contacts, etc. It is nice that when a friend sends a change-of-address notification that I can jump into whatever device I happen to be near at the time, put in the new info and -- voila! It shows up on all of my computers, my iPads and my iPhone with no fuss, no muss....it just works!