There's win 10 OEM, Win 10 home and Win 10 premium. Likely there are others I haven't seen yet.
 
I think I bought Win7 64 OEM on my last build and had no issues with it. I am leaning heavily toward Win 10 64 bit. Are there disadvantages to buying an OEM OS?  I'm not really sure what the other versions offer. For audio work what would you recommend?

For one thing your license will not be valid, since the OEM distributions for system builders are limited to new machines made for sale. The "system builder" licensing that first appeared with Windows 8.0, that allowed you to build your own machine and install the software was eliminated subsequently so that the OEM license requirement reverted to the old and present system. Doubtless they will install and activate but if the software police invade your premises... You would not likely be granted activation if you moved it to a computer or installed a new motherboard. Other than that you should be getting the same OS that you buy from one of the lesser assemblers, without the bloatware and special drivers etc. that they can pre-install.
 
"If you are building a system for your personal use or installing an additional operating system in a virtual machine, you will need to purchase a full version of Windows 10, available in FPP. Windows 10, Windows 8.1, and Windows 7 system builder software does not permit personal use, and is intended only for preinstallation on customer systems that will be sold to end users.*"
https://www.microsoft.com/oem/en/licensing/sblicensing/Pages/windows-licensing-for-personal-use.aspx#fbid=AOWYaxDTBX1
 

Yikes...I never knew that. I  used OEM on one build when windows was at version 7. 
 
I'll check that link and thanks! I'm now at a crossroads as to which non OEM to buy. Maybe that link will help. There's only around a 20.00 difference between Win 10 OEM and Win 10 Home edition.
 
It looks as if Win10 Home is the equivalent of the older "premium" version. This looks like my obvious choice so far. I don't need any of the additions in the pro version. I don't like the fact that updates are automatic though. This could really cause problems if it decides to update while I'm mixing.
https://en.wikipedia.org/wiki/Windows_10_editions
 

I have 10 (had it for almost a year in the "Preview" versions).  I go off line when I do anything in Sonar as I do not have anything that requires being on-line or at least on-line to the router.  Eliminates any potential problem. 
 
If you can find Win 7 or Win 8.1 at reduced price over Win 10, you can then do a "free" upgrade to Win 10 (same version as what the Win 7 or 8.1 is.  This may be cheaper. 

GO with Win 10 Pro x64. You get a bit more flexibility with updates.

If you custom build your machine and use a copy of Win10x64 OEM, you'll be fine.
Even if you upgrade components in the machine...
I've done that countless times.
Authorization has never been a problem.
One license on one physical machine.  Stick to that and you'll be fine.
 
 

Jim Roseberry
If you custom build your machine and use a copy of Win10x64 OEM, you'll be fine.
Even if you upgrade components in the machine...
I've done that countless times.
Authorization has never been a problem.
One license on one physical machine.  Stick to that and you'll be fine.
 
 

OEM is tied to the motherboard in W10 OEM.  They were flexible with W7. Not so sure with W10.

OEM has always been "Legally" licensed for the PC it was installed on, regardless of OS.  But its not a problem unless you want to change the motherboard and possibly other hardware like CPU.  I have home built PC's with OEM versions and one has been upgraded to Win 10 without problems.  Obviously if I changed the hardware on that PC I'll have to spring for a new OS.   No different than having a Dell, HP, or whatever brand PC with OEM version, its still only licensed for that PC but able to upgrade to the free Win 10.
 
Microsoft has been iffy on whether they would allow activation of an OEM version in Win 7.  Depends on the contact, some will activate the OEM OS with new hardware and some will not. 

Out of curiosity I went over to newegg and read the reviews on Win10......wow! This is enough to make me jump to a Mac. I don't like the idea that Microsoft can use my machine to mine information for whatever purpose, nor do I like the way your Win 10 machine acts as a server. They are using my paid internet connection and computer to gather info for their benefit. I want a recording machine but it looks like I'm aiding and abetting big brother. There certainly IS a reason they're giving away free upgrades.
 
Google and others have already been doing this for years, but now Microsoft has decided to make us all comply with their data mining in the new OS.
 
How this might affect recording remains to be seen, but if it's robbing my cpu while I need it for audio work, I feel used. What are your thoughts on this?
 
Thanks guys for those ideas. Sorry to divert a little from the main OS discussion but I think this is big.

First what "info" they get is anonymous.  However, as I noted I disable the Ethernet NIC (controller) when I run Sonar and thus there is no internet activity to potentially cause problems.  "Big brother" has been watching for years, there is data being "mined" in Win 7 and many application programs.  In many cases when you agree to the terms of a software package (most do not read them and just agree) you are also agreeing to allow them to track usage or whatever they say in the terms.