-Ripple Edit All and Ripple Edit Selection- (sorry, I know there are already posts about this, but....)
For me, it has been the single most useful feature update in recent history. It makes arranging and rearranging song sections so much easier. I can write a verse and a chorus, then quickly and easily slide in an intro or bridge with no effort at all.
It has literally changed the way I write songs.
I just have to remember to turn the feature back off after I'm done.
Some people have suggested having a toggle button on the Module Bar to turn the ripple editing on and off. Well that would be nice, but I hate to complain about anything, since this feature is so fantastically awesome.

And like with any new feature, the more I use it, the more I'll remember to turn it back off after using it.
Thank you Bakers, you continue to make Sonar better with every update!