Don't have an elicenser (to try the demo), don't want to have to use one: from what I've read, it's near impossible to get your software working again without buying another elicenser and software license should it malfunction due to no fault of your own.
 
Liked the idea of getting a faderport controller, and heard they work really well with Studio One (being made from the same company)

Cubase support is appalling .. well what I have experienced with them it is  but that might be down to me only being a Elements owner ..   6 weeks I had to wait to get a new elicenser after Windows Update,  I imagine the Dongle version is much better but why should I have to fork out again for the privilege. 

Tried Cubase and thought it had a huge learning curve. So I choose to go with S1, mostly record audio anyway except that I use some VSTi for drums and keyboard occasionally.

I bought Studio One last year when they offered a 50% crossgrade price. I currently use Sonar but I have been slowly getting up to speed with Studio one. I plan to create all new projects in Studio One when not using external gear. Sonar works better with external gear.

Answering the question from the other side. If I did mostly audio / tracking real instruments I would have gone for Studio One, the similarities to Sonar and the interface would have driven that decision, not the price. But 90% of what I do is MIDI so Cubase seems to be the best choice. The learning curve will be steeper for sure but there are a lot of features I want to get to grips with like the chord track which I hoped would have been added to Sonar at some stage.
 
Where price cam in was I may have gone for the Artist version of Cubase but the cross-grade made it a similar price to Pro, so no contest.

I went with Presonus.  Money didn't figure into it since I'm planning on using this DAW from now on.  I was willing to spend whatever it took to get what I  needed.  The truth is, I don't need much.  I do some audio and some midi.  I don't do much midi editing so i didn't need tons of depth there.  I do some audio editing, but again, nothing esoteric.  I also use 3rd party plugins almost exclusively, so that wasn't an issue.  Thus, Presonus came out the winner.

I went with Studio One because:
- Cubase requires a dongle. This simply doesn't not work for me as I move between multiple computers at multiple locations and am not interested in carrying a dongle around in my pocket, losing it, forgetting it, breaking it, etc.. Studio One allows five simultaneous activations and requires no dongle. 
- I've played around a bit with the free version of Studio One the past couple of years so I have some passing familiarity with it. As far as I know, Cubase has no free version or demo so all I know about the feel of the interface is what I can see in YouTube videos. 
- Studio One has been getting a lot of buzz the past few years -- more so than most other DAWs from what I've seen. Also, Studio One was relatively recently built from the ground up so has a fresher foundation. This all makes me think Studio One has a brighter future in terms of growth of what the DAW offers.
 

I've been using Studio One more and more over the past year and probably haven't even touched SONAR in several months.  It does what I need to and in my opinion does it very well. I also have Reaper and like it, but there are some things that Studio One does better and fits my workflow better.
 
I have no interest in Cubase, but if they had a downloadable demo, and didn't require a dongle, I would probably give it a try just to see. 
 
As for the handful of people who think that Studio One (or, really any other DAW except maybe Mixbus) sounds different/inferior to others, I'd like some of whatever you are smoking. 

Because of price? Yep, important part of my decision.
Studio One 3 Pro looks great and costs $125 (and no dongle).
 

azslow3
On-line authorization, forced included content, limited support for control surfaces. Doesn't that sound familiar?
 
Without me. And looking around, I do not see many choices. Fortunately, there is one...

I'm very curious, what are you going with? I'm still on the fence but am collecting options and, to an extent, opinions...