I have been using Sonar for years, and years. I am going to Pro Tools 11. The audio engine and buffering alone is way worth it. Sonar has come a long way but needs work still on the buffering and audio engine. Also I wonder why they haven't made X3 for Mac?

Because making a version for Mac entails them thinking they could grab enough Mac buyers to justify the cost of developing native cross platform code from the ground up. To have a firm share of market competing against apple made software you have to either :

1) Already have a huge market share prior to apple product becoming popular( pro tools, Avid, Cubase
2) Be a large enough company to offer complimentary products that dominate market like Adobe (Photoshop, illustrator and after effects work so well with premiere many opt for suite/cloud over final cut since they will be using the former products anyway)
3) Offer a product similar but with key specialized functions Apple does not do nearly as well ( Ableton, FL Studio)

What Sonar offers to PC users is probably not as big of a value to Mac users. Effects are debatable but no doubt the instruments bundled with Logic come out ahead mostly on the strength of a better sampler option. I prefer Sonar but I think it's a hard sell to someone used to Logic.

All the legacy DX code would have to go, meaning older but still useful plugs like Sonitus go bye bye. I'm sure peoplenot used to using would not care but just the presence of so much legacy code could create development expenses not worth return. I suspect Cakewalk/Gibson wants more stability before battling a jugernaut.

Separately, I'm sure people would like to know explicitly what you mean by "the buffering and audio engine"...

There are also considerations of dealing with Apple and the guidelines/restrictions they place on developers. Samplitude had announced the intention to produce a Mac version and started development, but eventually pulled the plug partly due to dealing with Apple's development issues.
 
I'm imagine that some of The Bakers have at least talked internally about Apple development and are more informed than most of us about the developmental and financial drawbacks to a Mac version of Sonar.

If your issue is buffering it's probably down to your audio interface. Development on the mac platform is expensive and risky. The market is already cornered anyway. BTW Pro tools is not immune to audio engine crashes, far from it.

CakeAlexS
If your issue is buffering it's probably down to your audio interface. Development on the mac platform is expensive and risky. The market is already cornered anyway. BTW Pro tools is not immune to audio engine crashes, far from it.

Having engineered many sessions in Pro Tools and having PT10 installed on the same Windows computer that runs Sonar, I get more tracks at lower latencies with Sonar than with Pro Tools. Also Sonar's PDC is more mature. However matters might have changed with PT11, I haven't upgraded it.

As to why Sonar isn't on the Mac, many reasons but there are also technical ones. Sonar works on really deep levels of Windows and the effort required to port it over to the Mac would be huge.
 
Another consideration is that the $199 version of Logic has really made competition difficult. I believe that all DAWs on the Mac, except for a program like Ableton that isn't a DAW in the conventional sense, have lost market share. Anecdotally, it used to be when I gave seminars and asked Mac users which DAW they used, it was mostly Pro Tools. Now it's mostly Logic.
 
IMHO Logic is the most "Sonar-like" of the various Mac DAWs, but that's of course a very subjective opinion.
 

Logic is certainly a lot more like Sonar than Pro Tools but very very different still.

ProTools has it's merits, but I found it much less stable and prone to pops and clicks when using lots of VSTi's. I suffer instability with synth-heavy projects in Sonar too, but far less.

I find pro tools to be the worst of the major DAWS for visrtual instruments.  Most Pro Tool users I know compose in other programs and mix and record in pro tools.