I don't remember. It was back a while but they keep making me upgrade so I forget when it all went wrong.
 
This post is in jest.

Really depends on your system.  Generally speaking, I get the impression those of us still on Win 7 or 8.1 experience less odd behavior than those on Win 10.  Just my opinion.

Since X3e I have never had anything happen that I would call "unstable" 
Weirdness yes, but un stable, no. 

Anderton
However I haven't updated to 2016.11 because of people reporting problems with the CA-2A, which I use all the time. I figured I'd just wait until it got fixed in December, unless there's a hotfix first.
 

kzmaier
I'm in a holding pattern with 10/2016, no trouble w/win10 all updates, asio driver.

+1
 
I'm holding on October (2016.10) for the time being.

X3 onward has been really good. Because I don't do a lot of heavy lifting, I can use a feature and not realize that I couldn't have used it 2 month earlier because it didn't exist. After a while the constant change just smears together and I can't really say what a specific update does.

ampfixer
After a while the constant change just smears together and I can't really say what a specific update does.

There's an easy explanation for that - Yoda is a master of time and space. To you, all versions of SONAR exist at the same time 

Anderton
Every version...since switching to an audio interface with better drivers.  
 
However I haven't updated to 2016.11 because of people reporting problems with the CA-2A, which I use all the time. I figured I'd just wait until it got fixed in December, unless there's a hotfix first.
 
Regardless. this is a meaningless question because there is no objective way to measure stability. If you measure it by crashes, I can't remember the last time I had a crash BUT I have a finely-tuned hardware and software environment. So that might mean SONAR is stable, or it might mean my computer is. Or it might mean I don't things my computer or SONAR doesn't like, although I exercise both pretty hard.
 
The most common issues with SONAR relate to third-party plug-ins and audio interface drivers. So if someone installs a problematic plug-in in March that causes SONAR to crash, they'll say February was the most stable release. If someone else installs that plug-in in August, they'll say July was the most stable release.

+1 to every statement here
 
 

I stopped at Manchester as well on Win7U.

Anderton
Every version...since switching to an audio interface with better drivers. 
 
The most common issues with SONAR relate to third-party plug-ins and audio interface drivers.

2016.10  Windows 7
I struggled with constant crashes the last few years until I changed my interface two months ago.  Now it's all smooth sailing. 
 

JonD
I get the impression those of us still on Win 7 or 8.1 experience less odd behavior than those on Win 10.  Just my opinion.

It seems that way to me too from what I read on this forum.  Is there any hard data on this, or is it all anecdotal?  So far it's kept me from upgrading to Windows 10.

Tell you what, if Cakewalk ever abandon Windows 7 so that SONAR no longer runs with it, I'm staying on the last version that does!