This is a matter of taste ultimately, but I thought some people might find it interesting.
I've gradually been pushing my software supersampling up at the expense of other things. I got everything running smoothly at 2x in-game supersample, sometimes having to drop to 1.5 in stations. Distant detail and text were amazing - great clarity, lovely stars, great readabilty. So it was a great, comfortable experience. My quality settings to achieve this were mainly medium.
After a bit of a break with the DK2 packed away, I got everything out again over the weekend to try out my new x52

. I decided to switch back to less demanding hardware supersampling (about 1.25x by forcing a custom resolution) and try putting all my settings back to Ultra (shadows on high), just to see what things were like when I started and found it all breathtaking.
For me there's no comparison. Having the ultra settings for the interior of the ship, the planets, the stations makes the immersion kick in 100%. It feels so real and gritty. Text still looks good but is noticeably less clear and distant space is not as sharp. But for me it still feels so much more real. I spend ages just flying round the outside of stations gawking at the detail.
Just some thoughts. If you can hit ultra at the expense of software supersampling, you know what all the text says, have good eyes and have spent enough time gazing at the stars, give it a try.
In terms of the rest of my setup and tweaks,
Titan X with small overclock
16gb ram
All CPU cores unparked
Physx forced to CPU
Extended mode
Default desktop colour settings
Default HUD colours
Some tweaks with SweetFX and GemFX, mainly antialiasing, based on the sticky thread here.
I always play in solo in the rift - i've found playing in open makes it impossible to tune your settings because other players cause judder
Most recent NVidia Driver
Most recent oculus SDK (hey, it worked, I didn't argue)