paulo
The reasons why I use it are pretty much covered in the other answers. The reason why you should use it is that here on this forum we have scook, who is like your own personal reference guide - ask any question you like and he'll not only know the answer, but has usually answered it before you finished asking the question, lol !  That and the fact that it seems that you're already buddies with Anderton, who also seems to have some degree of knowledge ;)
 
 

Well, Craig's covered a few of my songs and we've done a bit of collaboration online. I've only ever met him once in the flesh - that was in 2013 at a Line 6 conference in London. He's a lovely guy :)
 
And he's threatened to return to the UK again at some point....

MarkydeSad
And he's threatened to return to the UK again at some point....

So have I. Craig is likely to beat me though.

I agree with just about everything above. I started with Sonar about 10 years ago when I got frustrated with another DAW and the company that makes it, and CW/Sonar looked like a good replacement. I'd known about it for many years before that, but never used it, and I decided to take a chance on it. I found it very quick and easy to get started with, but extremely deep under the hood, and I have basically never had cause to regret the decision. I've experimented a bit with other DAWs in the meantime, and I still use Reason and Sound Forge alongside Sonar for the things they do well, and of course I enhance the toolkit with a few third-party additions (NI Komplete, Alchemy, various things from AAS and Izotope and IK Multimedia), but basically Sonar is home because it rarely lets me down and it keeps me interested. And I feel like the developers, and the community here, are from the same planet as me... if that makes any sense...

I initially bought it because I needed a good set of virtual instruments (especially drums) and a full effects suite. If I had my druthers at the time I would have stuck with a new version of the DAW I was using at the time but a) it cost over three times as much and b) did not come with nearly as many tools (so I would have had to buy them separately). Even the other DAWs in the same price range as Sonar did not have nearly the intrument/tools Sonar did.
 
I was concerned about the stability issue but dumped some cash into building a sooper powerful system (which I would have needed witht he other DAWs anyway) and hoped for the best. Fortunately (after some screwing around) it all worked and I now had a really useful starter set up for pretty much anything I wanted to do.
 
What I was not really expecting was the workflow and environment which I like a lot better than the "old" and "traditional" way of doing things. It just suits my crazyballs brain/methods better than the alternatives.
 
What has also happened is the toolset has expanded MASSIVELY even in the few short years I've owned Sonar saving me even more money that would have otherwise been dropped on third party stuff AND the forum has essentially taught me how to use it all (saving me a ton of money on expensive classes, books, tutorials, etc and making my learning experience more interactive and pleasurable).
 
I do think it's probably still a little shakier in stability terms than what I originally would have bought BUT since X3 those issues are very minor and I know what I can and cannot get away with. Compared to all the bonuses of using the program I can deal with those minor annoyances and really most of the other DAWs are going to have their own stability quirks as well (and I wouldn't have the support base I do around here).
 
Are there better DAWs? That's debatable. Are there better DAWs for ME? I don't think so... at least not for my general day to day usage/needs.
 
/true story

If you're on Windows, definitely agree with most of the ''pro'' above.  I'm now on Mac (not in the cult - but through a CustomMac) and now juggle between 3 DAWs (Pro Tools, Cubase and Logic). All have their strenghts and weaknesses.
 
Been with Cake since the mid-nineties and upgraded to most versions, until X1. But yet, my move to Mac - and reluctance of Cake to make a Mac version like most other DAWs made me quit. 
 
But definitely, if I'd eventually get back to Windows (very unlikely now...), Sonar would be in my main arsenal.  Very friendly with most equipment, and so on...
 
Just that I'm not too crazy with the new SaaS / subscription approach... But Pro Tools is going there too, and others may follow. At least, upgrades were not ''exactly'' at same time of the year ... and did not cost $200 per year... 
 
Rob