Just a bunch of random differences. Correct me if Im wrong at any.
I have sonar in the studio and Cubase at home. Sonar feels kinda like driving a truck, Cubase is more like a car. Its like sonar feels kind of more bulky like heavier on resources. The Cubase windows don't stay focused it keeps minimizing. You always need to right click on everything and set it to "always on top" I checked that option on just about everything in Cubase so the windows don't lose focus anymore, but it is annoying.
Cubase does give you what commonly used in an audio editor you just need to explore the menus instead of looking at the GUI. Sonar can feel cluttered depending on how you set your tools and windows. In Cubase you basically control whats seen on the tracks and the mixer. It has various options in the preferences menu, but not as much options in that area when not in the preferences, like docking resetting meters by clicking, dragging the GUI to see more stuff.. The mixer seems more customizable in Cubase. I think its less customizable than Sonar overall, but I said it before you'll probably want to customize Sonar first time using it. Sonars more easier to route also. Cubase has the pool, great for doing non destructive work. Cakewalk gives way better support to users, most
Steinberg users will say their assholes in terms of helping. Cubase is more wide spread in popularity so it probably will be quicker to learn from your net resources etc. I think sonar has better comping, than Cubase, but when recording takes stacked and stacked 2 is king.
Like someone said it doesn't let you use an external audio editor. I believe it used to, but not now. I'm more comfortable in sound forge in terms of audio editing. I just think Cubase's
Zoom is kind of wild for me, but you can always just open the audio editor and make changes and import the new take in the pool. Sonar still lets you use an external editor. Sonar comes with more instruments, but I think Cubase comes with more useful effects.
Automation is easier to draw in Sonar than Cubase imo. Cubase you can set your inputs and outputs of midi and audio to a specific project only. Sonar you can but less options.
Its a bunch of strong points and weak points comparing the two.