I've got a QS8, and I'm very happy with it. You're never going to get agreement from everybody, and you're never going to find the one synth that has everything exactly as you'd like to have it. I personally thought the QS8 had the best combination of sounds, feel, user interface, and construction for my tastes. It's my main keyboard, and it's working out quite well.

Best piano sounds? Maybe not, but not bad, either. I dig the organ sounds. And being able to play the four controller sliders like drawbars is great compared to other "main" synths. Best string sounds? Again, there may be better, but I got the Orchestral card and those sounds are pretty darn good, too. The QCards really multiply the sound rating of the synth in my book. I also got the Sanctuary Card and found a bunch of very cool sounds. Sure it's more money, but it's almost like getting another synth every time you get a card, and you can find them used for even less.

I haven't found any totally bad parts on this machine. Again, there's always little things you'd like to see done better, but some of those go directly to higher prices or other trade-offs. For the money, I like the QS8 the best.