First, I intend to use Sonar for as long as it is viable. I'm buying a new computer in the near future, at which time my current rig will be pulled offline and dedicated to Sonar.
 
I also intend to migrate full-time over to another DAW. I'm leaning towards Pro Tools 12.8 (not the HD version).
 
I already use Logic Pro X on my aging macbook, and I put up with it - but I don't love it. I use Reaper and/or StudioOne when I get involved in someone else's project and they want to stick with software they are comfortable with. I haven't touched Cubase for a long time, when a basic version came bundled with my MIDI controller years ago.
 
I'm fairly comfortable navigating between the different DAWs. I'm currently playing around with Pro Tools "First". Even with much of the editing and selection capabilities being disabled, it already feels the most comfortable/natural for me. Perhaps it's because my first DAW was a Pro Tools LE / Digi001 rig before I moved to Sonar 4.0 ?
 
Fast forward to right now, Sweetwater and Avid are running a 20% sale. Does anyone here work in non-HD Pro Tools? Would you talk me out of it? Or tell me to jump in?
 
Some concerns that I already have...
- iLok? Gross. The only silver lining is that I've been wanting to try some other iLok only plugins. I've heard horror stories of people getting locked out of their systems. But what's realistic?
 
- Limited track counts: Why do they bother? My system should be the one imposing such limits, right? It's a transparent money grab trying to get people to adopt the HD lifestyle, right? At the same time, I could definitely use more discipline when it comes to reducing my track counts.
 
- Plugin formats: I use lots of Waves plugins, and several other VST's. It looks like Waves is compatible. And it looks like there are VST wrappers for the rest. Does this affect performance?
 
- If you've recently moved to Pro Tools from Sonar, would you do it again? Or do you regret it?

I've worked in non HD Pro Tools for quite a while and 
it's definitely an "ok" DAW.  It will do the job.  I
certainly wouldn't talk you out of it.  If you have an 
upgrade path that would help bring the cost down.
Another option is to "Subscribe" for a year, before committing
to buying a "Perpetual License", which is what I had.

It's all relative, and, if YOU feel comfortable working there
then do what is best for you!  That's the BEST advice you
can get 

-iLok worry is unsubstantiated
-limited I/O is a big problem, arbitrarily imposed by AVID so they can sell hardware
-most modern plugins come with .aax versions. For those that don't, wrappers are available, like Blue Cat Patchwork

Pro Tools will be very frustrating at first to accomplish basic tasks. Right Click for a context menu barely exists. Some features can only be used with key commands - no problem, the key commands list is only 60 pages long... MIDI editing is limited, but not as bad as some people suggest (with recent improvements). Big learning curve ahead.
 

Well, I went ahead and ordered it. I figure I will either hate it, or learn to live with it. Like I said before, I used back up through version 5 point something or other. I liked it then, but it was all I'd been exposed to. 
 
I primarily work with audio; multi-tracked live acoustic drums, guitars, basses, keys, vocals, etc. I do use a lot of soft synths, but mainly just to generate sounds after capturing a "live" MIDI performance. If I can fix the occasional 'flub' in a MIDI track, then that's a bonus. Even when I do occasionally dip into an EDM type experimentation, it's all very much a "performance", and usually involves straight up audio tracks. 
 
Fortunately (or unfortunately depending on your perspective), my needs are very humble compared to a lot of you guys playing around deep in the weeds. The only real "trick" that I've really incorporated into my production style is ARA integration for Melodyne. I will not be able to do this in Pro Tools (or at least not as easily).
 
It's hard to love and rely on Sonar so much, and know that it probably won't always be there for me.