Resonant and Gball mentioned some aspects of Macs. I have used them forever now and I agree they are less headaches.
A lot of people look for new, all in one, or portable solutions. Let me offer a different take.
A well built computer should last 8 years or more and still have reasonable power, or have the capability for upgrades. (Yes - IT people might consider an investment every 3 years to be normal and I suppose it is if you are buying middle of the range PCs for office work)
So if you are looking for a computer, getting a laptop or an all in one like an iMac maybe won't be your best dollar spent.
At this point 6 core or greater processors and 32 GB of ram or more make the best sense for future proofing yourself. Every year
Mac Pro 5,1 -
There is a HUGE supply of Mac Pro 5,1 models out there. They are getting long in the tooth and there are some issues with interfaces as they don't have thunderbolt. They can be found on eBay, and other sellers like www.macsales.com
They are cheap for the amount of power. And lots of spare parts around if you have a problem - as there is no warranty.
They do have great expandability and power. My 2010 12 Core x 2.66 ghz has 5 hard drives in it, + 2 x SSDs for sample streaming on PCI cards, and 32 GB ram.
The only reasons I will eventually upgrade:
1) The video card will need an upgrade to run OS X Mojave and beyond because it is not "metal" compatible. That's $400.
2) The lack of Thunderbolt ports will be an issue. I will eventually move to a UA Apollo interface and discard my existing Apogee Duet 2 and UAD Quad PCI card.
3) 32 GB of ram could be expandable to 128 GB but I would likely save the $230 for the upgrade to 64 GB and put it towards the new setup.
I will either go to a Mac Pro 6,1 (again cheap $$$) or go to a new Mac mini (current specs).
Mac Pro 6,1 -
The current "trash can" will be off the market this fall when the newest greatest and unbelievably powerful and expensive Mac Pro 7,1 comes out. This means that all retailers and resellers maybe getting rid of them quickly and at good prices, and used prices will probably take a hit.
This model has upgradable processor, flash drive, RAM and Thunderbolt 2 ports (so will be behind the current spec of Thunderbolt 3).
This would be a great intermediate buy if you want Thunderbolt ports, and ability to use OSX Mojave and beyond and want RAM up to 128 GB.
Caveat - at some point Apple finds a way to make old models "not current". Recently that has been with limiting the recent versions of OSX that can be used.
So either of these used options may eventually have issues if you are tied to upgrades with the latest and greatest.
But if what you have works, and you can still get a lot accomplished then upgrading isn't all its cracked up to be.
Any Mac on the Apple store that is refurbished will save you 10% straight off. And you get full warranty.
If it were me, I would never buy an iMac. They have issues with overheating, and while they can be expanded it requires taking it apart.
For me a laptop is also not worth the extra money as I don't do stuff on the go, on airplanes. I sit in my studio.
At current the price performer that Apple sells is the current revision of the Mac mini.
Spec it out with 64 GB Ram, 3.2 Ghz i7 6 core processor (need i7 for hyper threading and virtual cores basically twice the power of i5), and at least 1 TB flash drive. It will run you $3k. It has Thunderbolt 3 ports.
I estimate that this machine will be current with OS X upgrades and having enough power to run reasonably large sessions till 2025 or after.
If you can't be bothered to drink the Apple Kool-aid, that's fine too.
I would get a builder like Vision DAW to build you a powerhouse machine, or if you are handy, build it yourself with parts from New Egg or Tiger direct.
If you go with a builder ike Vision DAW - they usually take care of issues and make sure there is compatibility. Building things yourself you can screw it up.