Stagg cymbals are very competetive...especially with the price. Most stagg models are already casted. They say that stagg is "the poorman's Sabian." which is true, since the price is very affordable. With regard to the sound...again it depends on your ear...
I already have 2 staggs, a 13" hihat and a 16"crash. I really enjoyed my hats back then but I got used to it so I sold it...for my crash, it's still with me.
What I haven't heard is the black series of Stagg, it's like the K series(not exactly sure). I should drop by TMS soon....
With Sabian, I only have an 18" xs20 crash which I also enjoy... what I like most is the B8's. that's what we use in our church.
Bottom line is, your ear is your best friend when you're pickin cymbals...whether it be Sabian or Stagg. You also have to consider your "pocket-power".
HTH