I bought both S1 and Cubase.  Cubase is disappointing for lack of ARA support and no indication that they are planning to add it, despite boatloads of user requests.
 
Before I had ARA I didn't know I needed it, but once you have it it's hard to give it up!
 
So I'll likely use S1 for many things and Cubase when I need the advanced MIDI capabilities. 
 
I also have Reaper and it's usable as well, though I never gravitated toward it, always used SONAR as my main DAW.
 

Cubase suffers from the same aging code issues that Sonar did. It is certainly fully featured, but I find it slugish, convoluted and full of quirks. For me, SO3 is at the right age - new enough to be clean and fast, but far enough along in its development that I can do all I need to. 

I'm not choosing either. But if I had to choose between the two options in the OP, it would be Cubase because that is the better choice for the way I like to work/play. It may not be yours, and I can appreciate that someone else will choose differently.

I honestly don't get the argument that it's bad to have mature code.  In fact that's usually a good thing.
 
I've been impressed at the feature content of StudioOne for how relatively young of a product it is, but it's just lacking in feature set compared to Sonar and Cubase.  Some people don't need or don't care about that feature set, and if it works for you, you can do some really cool stuff with it.
 
But there are some functions that StudioOne is not even close to matching the functionality of Cubase.  Midi is only one area.  The time stretching algorithms and tempo track functions built into Cubase simply blow Studio One out of the water.  Even with the ARA integration and Melodyne you can't match some of those functions with the ease that you can in Cubase, and I'm only scratching the surface.  That comes with advanced coding that goes into Cubase, and from it's long history.
 
I'm not saying this is good or bad, Studio One is a good product for a huge number of people, but those thinking it will "catch up" with the big guys are not really looking at the differences in lifecycle development for these two products.  Studio One has 3 to 4 years in between major releases, where Cubase being a professional grade product is on a year to year development cycle.
 
I now have both products and  will continue to use Studio One for certain things.  I love the mastering functionality in it, and if you are trying to compile an album, it's the perfect tool and you'd spend another DAWs worth of money trying to get that same functionality.
 
However the lack of midi functionality and lack of a real built in channel strip makes me want to do my work elsewhere.  But for folks just getting into home recording, StudioOne would probably be my number one choice for them, as there's not a big learning curve.
 
I find both Studio One and Cubase really lacking at integrating with Windows 10, and have a very apple centric layout.  That does bug the heck out of me, and is probably the biggest thing I miss in Sonar.  There's no native full screen mode in Windows for either which sucks for laptop users, and the touch screen integration sucks on both for those using Surface tablets or other Windows 10 touch screen devices.  Sonar really had the best touch screen integration and they had it since X2.  Studio One's touch integration is slightly better than Cubase, but it's extremely buggy, but the project page navigation with touch screen is similar to what was in Sonar, just not as well implemented.  However both Studio One and Cubase are better than Sonar for having a dynamically adjusted throw on the faders.  This is extremely important if you want to do any sort of touch screen automation.  Sonar had a fixed length fader and the throw on the fader was really too small for working on surface tablets and such.  Studio One does have the iPad/Android control app as well, but there are other 3rd party control mobile apps that work with Cubase.
 
You can't go wrong with either, but find one that really fits your needs and budget.  As a general rule I have told people that if you work more with Midi, Cubase is the better route, if you work more with Audio clips you might find Studio One more appealing and easier to work with.

Studio One.
 
I have Ableton which excels at Midi and was mostly exporting tracks to Sonar for final mixing due to Softube Console 1 support. Studio One has comping, ARA Melodyne support, and full Console 1 support so it made the most sense for me.
 
... and just to say it, I said the lifetime updates made no business sense at the time. :) However, I did not say they made no going-out-of-business sense... :(

tenfoot
 
For me, SO3 is at the right age - new enough to be clean and fast, but far enough along in its development that I can do all I need to. 

Indeed, that was my thoughts, albeit 3 years or so ago (v3), and it's gotten better by leaps and bounds.

I went for Studio One 3 similar work flow to Sonar with a little Cubase best of both words, the DAW is growing which is a plus. Many people have migrated over so easier to work with other people. Least I wont get no I never heard of that, then the look. When you explain they still look at you. Least I have a DAW quick to load onto your computer doesn't take up much space yet is powerful and efficient. Newish code it is all relative.

Bought Cubase 4 in 2006, used it for a couple of years, then said sayonara! Dongle wasn't a big deal, just leave it plugged in a slot on a USB splitter.  I think I bought Reason after that, which lasted only a couple of years. Then Reaper until I noticed the Sonar expansion.   Problem was a user unfriendly workflow and no support in forums, videos or literature.  I tried S13 for a few days, watched many videos, read lots of manuals and forum posts, then bought it.  Lots of positive comments in earlier posts that I agree with.  I just don't do much really technical stuff so a simpler interface is good.  Editing the band 8 track, making albums and songs with audio and midi... and the project editing feature for mastering is nice also.  
 
Like I said in another forum, buying this now means that something will happen with Sonar to resurrect it.  Anyway, price was alright so now I have an alternate instead of using Reaper.

denverdrummer
I honestly don't get the argument that it's bad to have mature code.  In fact that's usually a good thing.

 
I don't think it's so much a slam against mature code as it is an argument against bloat.  Most of the times I see mentions of "mature code" it is followed by complaints about outdated plugs and system components that would probably require coding from ground up to clean up the less desirable.  For Sonar that is probably at least part of the reason the Mac port didn't move forward . I'm sure other factors like how unlikely it would be to to compete with Logic's price. Programs that have successfully made the jump from being a longtime windows only program to Mac usually offered something truly unique or some incentive impossible otherwise.  Best example I can think of is Adobe Premiere and Audition.  Both were windows only for years .  Initially Premiere could not compete with final cut on MAC, until creative suite  created a bundle with the monopolized tool every visual artist uses to some degree; photoshop.  The ever tightening integration between  these programs  made this bundle more and more attractive .  Very few companies could reproduce this dynamic.  FL studio (still in beta)  will likely enjoy similar success because there is no MAC equivalent.  
 

NO! I like Studio 1 way better than Cubase. Not for price for the DAW