Considering only reverbs included with Sonar (Producer) X2...
 
My go-to has been Lexicon Pantheon for years.  Perfect Space is nice, but it's only 32-bit and I hate working via BitBridge.  It is, however, the only included reverb capable of panning the wet signal via a Send Pan (unless I'm missing something??).
 
Has Breverb become the reverb of choice for anybody?  Besides the two I mentioned above, I think this only leaves Sonitus (at least for 64 bit).

Breverb is a great addition to what's included in Sonar. It's easy to use.

You can visit YouTube and see some tutorials and demos on it and see and hear it applied on some nice examples.

I have the included reverbs of course and have picked up some third party ones. The TSAR reverb that is part of the Softube Mix Bundle that conveniently also has ProChannel modules is also one of my mainstays.

Even though I have additional third party reverbs I find myself getting desired results from Breverb and I use it a lot.

I never like the Lex.  Maybe I didn't give it a chance.  PS is great and was my main verb - for vox and lead stuff.
 
Breverb is nice and the best thing available in my opinion that comes w/ SONAR.  The softube reverb is at least as good - if not better.  If you mixed the mix bundle softube is having a half price sale now, I believe.
 
My go-to verb these days is the hardware unit that comes w/ the TC Konnekt 48.  Algos taken from their 4000 series.  Great reverb that sounds clear and doesn't fog up the soundstage.  Needless to say, that doesn't come w/ sonar.
 
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For big, spacey reverbs (cf Trevor Horn) I prefer to use Reaktor's Space Master 2 (stock with Reaktor). For more realistic rooms, I still have a soft spot for Perfect Space, although I find myself using the "built in" Breverb more and more.
 
Edit - Oops, I didn't read OP's subheading! Scratch Reaktor!

I too use the Exicon Pantheon a lot... I know there have been a number of expletive who don't like it, I find it a very easy to use and pleasant sounding reverb... Much like the 224 I used to use... A bit on the bright side by default, but mixes in very well.

That said, I have been using the Overloud Breverb which came with Sonar and find it quite nice. Warm and deep...

I also use Perfect Space on occasion.... And I've found these three cover my needs nicely...

Keni

I have strayed away from the reverbs included in SONAR. FWIW most of the newer reverbs that I have encountered are true stereo just like BReverb. Parallel stereo reverb does not appear to be very common anymore. Might as well use two mono reverbs.

Yea,  I'm not a good mixer,  but Scook commenting on the stereo issue reminds me of issues I had with Lexicon.  If I record an instrument on a mono track the Lexicon sounds great,  but the stereo sound of BReverb works way better for me especially with Orchestral instruments and larger sounding spaces.  The Lexicon feels like too much on vocals for me even dialing it back, perfect space tends to work better there.  BReverb has seemed to be more usable in more situations then Lexicon.
 
Just my thoughts...

I use to use Lexicon brfore reverb out of laziness to audition 3rd party ones. I always thought it sounded kinda metalic & steril, and thought it lacked in stereo width. In my opinion, Breverb blows lexicon away with warmth and good stereo width

I'm not on X2...still hanging in there with X1.
 
That said... my go to verb is Cake's StudioVerb2.   I have used this verb on just about every one of the projects I have ever worked on.
 
To my ears, it just sounds good. Therefore, I use it.

When recording without using soft synths, I use the reverb in my audio interface.
 
When recording using soft synths (so I need to monitor from Sonar), I use breverb because it doesn't add latency the way perfect space does.
 
When mixing I either use Breverb or Perfect Space. I'm attached to perfect space and have used it for years.
 
But for a while now I've been using Breverb and I go to it more and more.