Having tried Persian food at various places, I find that the quality of most places are similar. Kish distinguishes itself by having a few menu selections that are not available at other places. Other than that, I think their portion sizes are good. As an example, Super Tehran's kebobs are slightly smaller but also a little cheaper. Kish is about $1 higher but the meat portion is better so it's worth it.
I've had Vaziri, Kebob Torsh (not available in most Persian places), Kebob Maksoos (also not available in most places) and lamb shank.
-The Vaziri (koobideh + chicken leg) is good. They grilled it really well.
-Torsh is an experience by itself. They've really tenderized the meat and the pomegranate marinate they use is very delicious.
-Maksoos is basically koobideh but they stick a few pieces of chicken on it. Not bad but not significantly different from a regular koobideh
-Lamb shank was a little disappointing. We got a piece with a big bone. Taste wise it was ok.
Like I said, I find most persian places are very similar to me. The seasoning they use seems to be standard so it's all about grilling it right and not skimming on portion. Kish stands out for me because they have tables, reasonable prices, and a few dishes you can't find elsewhere. I'd come again if I want another Kebob Torsh or Maksoos.