lifetime updates. 

For me the performance enhancements like plugin load balancing,
 

I know a lot of people don't like it but the changes to the synth rack. Coupled with browser improvements.

I forgot lifetime updates.
 
Still don't know why they did that unless it was to lock in SONAR disciples that praise Cakewalk elsewhere by default. 

mixmkr
lifetime updates. 

+1

for me, it might be the smart swipe actually.  I hate clicking and clicking.  swiping was an awesome idea!   
 
 

The best enhancements are the ones you don't even have to think about, so load balancing gets my vote.
 
Second favorite came as a surprise: TH3. I thought I was covered for amp sims, and at first glance this one's kinda basic, but it's become my favorite for clean and semi-clean tones.

hover craft
talent button
 
 
 
what? youze guize dinnit getz thoze?

1. Melodyne multi track integration
The time saving of this one feature is staggering.
 
 
I'm mixing a friends track which is in free time with many complex overdubs.
Previously this would have taken weeks to months of work.... did it in an afternoon.
 
I'm not sure it was even possible to make the song as good as it is now without this feature.
 
2. Plugin load balancing
Given how complex my friend likes his music... his tracks have a helluva lot of plugin's! Load balancing is the difference between mixing slowing to a crawl with constant painful dropouts... and it being a pleasure to mix. 
 
We have nearly finished mixing a 12 track album in the Christmas holiday period; that would not have been possible last year.
 
Thank you to everyone involved from Cakewalk and third parties.
 
P.S. You've made an old 70's prog rocker and his protege / sound engineer very happy.

As I was crawling out of bed this morning I remembered background VST scanning.
I like the fact that an installer or myself can plop a dll in a folder in the vst scanning path and the background scanner detects I did it and adds it to the party.
 
Very nice Mr. Borthwick, very nice.