Asking which workflow is superior is sort of hard because an experienced Sonar user will be fast and fluent with the Sonar workflow hence will say yes it is good. They may find Studio One say a little awkward to use. An experienced Pro Tools user is also going to feel at home on PT and say it is good but they may find other DAW's a little uncomfortable.
Me however, slick and fast on Studio One therefore I will tell you the workflow is also good. I find Sonar uncomfortable to use now when and if I have to go to it for any reason. Workflow will be good on many DAW's, basically it is related to how well you know your program. Simple as that.
Studio One mixing is as good an any. Horsepower is related to the computer not the program.
(UAD when engaged really takes mixing into serious territory too) The standard plugins will get you a fantastic mix, period.
(Remember it the engineer that achieves that only) But as many of us have third party stuff, that is how you are expected to use it. Rather than give you a whole lot of Pro Channel type modules, they give you a solid frame to plug your own things in there. And I do, and they all work very well too in that situation.
It is nice too send some great sounding tracks straight through to the stereo mix too without the slightest interference. Pro Channel and Console emulators totally unnecessary.
It is great too that programs like Sonar offer so much as standard. Means you don't have to go out and buy the extra stuff and the standard is high with the Sonar built in stuff too. Just two different ways of approaching it.
But if you are wanting to compare DAW's and find out, it is time as we have been saying to use them and see which one fits your vibe, feel and personality. No amount of discussion is going to get you to that point.
Only listen to people who are on the latest version of Cubase
(and any other DAW) as well. Sorry people but Cubase SX3 and around that time sort of does not cut it does it. Bit like comparing to the first version of Sonar. Do you want someone to base their impression on the first version of Sonar or the latest version. It is imperative that you examine all the very latest versions of all the programs of interest. Quite large improvements have been made in very recent updates to some programs out there.
It is also important to realise that all DAW's have features that are well beyond those in their counterparts. It is silly to think that there is one that is so far out front and the others are way behind. It is not like that. It is a bit like a running race and the runners are all about a meter apart really, moving at the speed of light and taking it in turns to be the leader out front, it is usually only for a second or two!